setup-python: Version 3 was not found in the local cache

Using Codebuild for Github Action Runners (self-hosted in Codebuild). The `setup-python` action tries to search for a local Python, but it couldn't find any Python 3.

I'm using the `aws/codebuild/standard:7.0` image. Is there any way to get an Ubuntu image with a python version pre-installed? Because of how codebuild works with github, I can't really specify a buildspec, it gets overriden by github

Start by inspecting the aws/codebuild/standard:7.0 image and how its installed runtimes are exposed to the setup-python action on a self-hosted CodeBuild runner. Check whether the image definition or documented configuration addresses Python 3 availability without a buildspec. Done means confirming the supported image or configuration path and documenting the result.

Written by the indexing model from the issue text.