Create an issue on nightly CI run failure

[dario23]

Implements #299

fixes #299

[dario23]

create issue correctly skipped for the pull request build; i used the same github.event_name == 'schedule' as we do to skip setting up the latest nightly toolchain for non-nightly builds, so i hope that does its part, but not sure if we can explicitly test the other way before merging (and hopefully before the next nightly build failure).

[JohnTitor]

Have you tested the script on your fork or somewhere else? Overall looks good but I'd like to make sure that variables in the script work fine.

[dario23]

alright, tested now, see also the latest force-push.

• failing run which initially created an issue (in my fork): https://github.com/dario23/rust-semverver/runs/6638053575
• later failing run not creating another issue: https://github.com/dario23/rust-semverver/runs/6638053575

[JohnTitor]

Awesome, thanks for testing!
@bors r+

[bors]

📌 Commit 02cba1d has been approved by JohnTitor

[bors]

⌛ Testing commit 02cba1d with merge 3884350...

[bors]

☀️ Test successful - checks-actions
Approved by: JohnTitor
Pushing 3884350 to master...