Unable to access behind proxy

When I run `gren changelog -B` on a public repo, I do get the following:
```
Options:
Tags: empty
Prefix: empty
Template: [object Object]
Prerelease: false
Generate: false
Quiet: false
Override: false
Debug: true
Ignore labels: empty
Ignore issues with: empty
Ignore commits with: empty
Group by: false
Milestone match: Release {{tag_name}}
Changelog filename: CHANGELOG.md
Username: NCI-Agency
Repo: anet
Token: ********************************'
Data source: issues
Include messages: commits
Ignore tags with: empty
Limit: 30

🤖 - Generate changelog file:
===================================
WARNING: Looks like you don't have network connectivity!
⠋ Getting the list of releasesTypeError: Cannot read property 'status' of undefined
at handler (/usr/lib/node_modules/github-release-notes/node_modules/github-api/dist/components/Requestable.js:366:40)
at
⠋ Getting the list of releases
```

At the same time, directly calling the api works:
```
curl -X GET \
https://api.github.com/repos/NCI-Agency/anet/releases \
-H 'accept: application/json' \
-H 'authorization: token ********************************' \
-H 'content-type: application/json'
```

I am behind a proxy. Any help would be appreciated!

Start with the `gren changelog -B` path that requests the GitHub releases endpoint, then inspect the reported `node_modules/github-release-notes/node_modules/github-api/dist/components/Requestable.js` failure and compare it with the working curl request. Done means the command can retrieve releases through the reported proxy setup without the network warning or `status` TypeError.

索引モデルが issue の本文から書いたものです。