Jekyll website fails to publish to Static Web App with unknown exception

When trying to build and deploy a Jekyll-based website via Github Actions, the `Azure/static-web-apps-deploy@v1` fails with the message `An unknown exception has occurred` after `Uploading build artifacts.`. This happens when changing from the Github hosted build runner (`ubuntu-latest`) to a self-hosted runner. When using the `ubuntu-latest` build runner it works as expected.

I am unable to find a lead to what is actually wrong based on the build runner `_diag` log files.

**To Reproduce**
Steps to reproduce the behavior (based on https://docs.microsoft.com/en-us/azure/static-web-apps/publish-jekyll):
1. Create a clean Static Web App in Azure
2. Connect it to a Github repository
3. Change the build runner from `ubuntu-latest` to a self-hosted runner
4. Start Github Action by pushing to the repository

**Expected behavior**
Either a clearer error of what is actually wrong, or uploading to the Azure Static Web App without a problem.

**Device info:**
Self-hosted runner:
- OS: Ubuntu 20.04.2 LTS
- Version: Runner version 2.281.1

**Logs:**
```
Run Azure/static-web-apps-deploy@v1
with:
azure_static_web_apps_api_token: ***
repo_token: ***
action: upload
app_location: ./
output_location: _site
/usr/bin/docker run --name e84f5cd88c4efc90b34929aefb850384369eef_5f967b --label e84f5c --workdir /github/workspace --rm -e INPUT_AZURE_STATIC_WEB_APPS_API_TOKEN -e INPUT_REPO_TOKEN -e INPUT_ACTION -e INPUT_APP_LOCATION -e INPUT_API_LOCATION -e INPUT_OUTPUT_LOCATION -e INPUT_API_BUILD_COMMAND -e INPUT_APP_ARTIFACT_LOCATION -e INPUT_APP_BUILD_COMMAND -e INPUT_ROUTES_LOCATION -e INPUT_SKIP_APP_BUILD -e INPUT_CONFIG_FILE_LOCATION -e HOME -e GITHUB_JOB -e GITHUB_REF -e GITHUB_SHA -e GITHUB_REPOSITORY -e GITHUB_REPOSITORY_OWNER -e GITHUB_RUN_ID -e GITHUB_RUN_NUMBER -e GITHUB_RETENTION_DAYS -e GITHUB_ACTOR -e GITHUB_WORKFLOW -e GITHUB_HEAD_REF -e GITHUB_BASE_REF -e GITHUB_EVENT_NAME -e GITHUB_SERVER_URL -e GITHUB_API_URL -e GITHUB_GRAPHQL_URL -e GITHUB_WORKSPACE -e GITHUB_ACTION -e GITHUB_EVENT_PATH -e GITHUB_ACTION_REPOSITORY -e GITHUB_ACTION_REF -e GITHUB_PATH -e GITHUB_ENV -e RUNNER_OS -e RUNNER_TOOL_CACHE -e RUNNER_TEMP -e RUNNER_WORKSPACE -e ACTIONS_RUNTIME_URL -e ACTIONS_RUNTIME_TOKEN -e ACTIONS_CACHE_URL -e GITHUB_ACTIONS=true -e CI=true -v "/var/run/docker.sock":"/var/run/docker.sock" -v "/home//_work/_temp/_github_home":"/github/home" -v "/home/[redacted]/_work/_temp/_github_workflow":"/github/workflow" -v "/home/[redacted]/_work/_temp/_runner_file_commands":"/github/file_commands" -v "/home/[redacted]/_work/[redacted]-website/[redacted]-website":"/github/workspace" e84f5c:d88c4efc90b34929aefb850384369eef
DeploymentId: bb6d49d5-bbfb-4f9d-a9cf-fdc20c620931

App Directory Location: './' was found.
No Api directory specified. Azure Functions will not be created.
Starting to build app with Oryx
Azure Static Web Apps utilizes Oryx to build both static applications and Azure Functions. You can find more details on Oryx here: https://github.com/microsoft/Oryx
---Oryx build logs---

Operation performed by Microsoft Oryx, https://github.com/Microsoft/Oryx
You can report issues at https://github.com/Microsoft/Oryx/issues

Oryx Version: 0.2.20210410.1, Commit: e73613ae1fd73c809c00f357f8df91eb984e1158, ReleaseTagName: 20210410.1

Build Operation ID: |vIm1zR1gLkk=.21c435f0_
Repository Commit : a111fc4e29749d74d298948890c0722c303948fd

Detecting platforms...
Detected following platforms:
ruby: 2.7.2
Version '2.7.2' of platform 'ruby' is not installed. Generating script to install it...

Source directory : /github/workspace
Destination directory: /bin/staticsites/ss-oryx/app

Downloading and extracting 'ruby' version '2.7.2' to '/tmp/oryx/platforms/ruby/2.7.2'...
Downloaded in 1 sec(s).
Verifying checksum...
Extracting contents...
Done in 2 sec(s).

Using Ruby version:
ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-linux]

Using Gem version:
3.2.9

Running 'gem install bundler'...

Successfully installed bundler-2.2.27
1 gem installed
Running 'bundle install'...

Don't run Bundler as root. Bundler can ask for sudo if it is needed, and
installing your bundle as root will break this application for all non-root
users on this machine.
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Using bundler 2.2.27
Fetching public_suffix 4.0.6
Fetching eventmachine 1.2.7
Fetching faraday-net_http 1.0.1
Fetching multipart-post 2.1.1
Fetching rexml 3.2.5
Fetching ffi 1.15.0
Fetching http_parser.rb 0.6.0
Fetching rb-fsevent 0.10.4
Fetching forwardable-extended 2.6.0
Fetching colorator 1.1.0
Fetching concurrent-ruby 1.1.8
Fetching ruby2_keywords 0.0.4
Installing colorator 1.1.0
Installing faraday-net_http 1.0.1
Installing multipart-post 2.1.1
Installing ruby2_keywords 0.0.4
Installing rb-fsevent 0.10.4
Installing forwardable-extended 2.6.0
Installing rexml 3.2.5
Fetching liquid 4.0.3
Fetching mercenary 0.4.0
Fetching rouge 3.26.0
Installing public_suffix 4.0.6
Fetching safe_yaml 1.0.5
Installing http_parser.rb 0.6.0 with native extensions
Installing eventmachine 1.2.7 with native extensions
Fetching unicode-display_width 1.7.0
Installing concurrent-ruby 1.1.8
Fetching jekyll-paginate 1.1.0
Installing mercenary 0.4.0
Installing liquid 4.0.3
Installing safe_yaml 1.0.5
Installing unicode-display_width 1.7.0
Installing ffi 1.15.0 with native extensions
Fetching webrick 1.7.0
Fetching pathutil 0.16.2
Installing jekyll-paginate 1.1.0
Fetching faraday 1.3.0
Fetching terminal-table 2.0.0
Installing rouge 3.26.0
Fetching addressable 2.7.0
Fetching kramdown 2.3.1
Installing pathutil 0.16.2
Installing terminal-table 2.0.0
Installing webrick 1.7.0
Installing faraday 1.3.0
Installing addressable 2.7.0
Installing kramdown 2.3.1
Fetching i18n 1.8.10
Fetching sawyer 0.8.2
Installing i18n 1.8.10
Installing sawyer 0.8.2
Fetching octokit 4.20.0
Installing octokit 4.20.0
Fetching jekyll-gist 1.5.0
Installing jekyll-gist 1.5.0
Fetching kramdown-parser-gfm 1.1.0
Installing kramdown-parser-gfm 1.1.0
Fetching sassc 2.4.0
Fetching rb-inotify 0.10.1
Installing rb-inotify 0.10.1
Fetching listen 3.5.1
Installing sassc 2.4.0 with native extensions
Installing listen 3.5.1
Fetching jekyll-watch 2.2.1
Installing jekyll-watch 2.2.1
Fetching em-websocket 0.5.2
Installing em-websocket 0.5.2
Fetching jekyll-sass-converter 2.1.0
Installing jekyll-sass-converter 2.1.0
Fetching jekyll 4.2.0
Installing jekyll 4.2.0
Fetching jekyll-include-cache 0.2.1
Fetching jekyll-feed 0.15.1
Fetching jekyll-sitemap 1.4.0
Installing jekyll-include-cache 0.2.1
Installing jekyll-feed 0.15.1
Installing jekyll-sitemap 1.4.0
Fetching minimal-mistakes-jekyll 4.22.0
Installing minimal-mistakes-jekyll 4.22.0
Bundle complete! 7 Gemfile dependencies, 41 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
Running 'jekyll build'...

Configuration file: /github/workspace/_config.yml
Source: /github/workspace
Destination: /github/workspace/_site
Incremental build: disabled. Enable with --incremental
Generating...
Jekyll Feed: Generating feed for posts
Pagination: Pagination is enabled, but I couldn't find an index.html page to use as the pagination template. Skipping pagination.
done in 0.647 seconds.
Auto-regeneration: disabled. Use --watch to enable.
Preparing output...

Copying files to destination directory '/bin/staticsites/ss-oryx/app'...
Done in 0 sec(s).

Removing existing manifest file
Creating a manifest file...
Manifest file created.

Done in 105 sec(s).

---End of Oryx build logs---
Finished building app with Oryx
Using 'staticwebapp.config.json' file for configuration information, 'routes.json' will be ignored.
Zipping App Artifacts
Done Zipping App Artifacts
Either no Api directory was specified, or the specified directory was not found. Azure Functions will not be created.
Uploading build artifacts.
An unknown exception has occurred

For further information, please visit the Azure Static Web Apps documentation at https://docs.microsoft.com/en-us/azure/static-web-apps/
If you believe this behavior is unexpected, please raise a GitHub issue at https://github.com/azure/static-web-apps/issues/
Exiting
```