Commit changelog after updating with release date fails, indicating wrong branch is checked out

[weierophinney]

Bug Report

Q	A
Version(s)	1.2.2

Summary

When issuing a release for laminas-mail, I received an error indicating it could not commit the changelog file back to the release branch, as that branch was not currently selected:

• https://github.com/laminas/laminas-mail/runs/977187215?check_suite_focus=true#step:4:14

How to reproduce

Close a milestone, and wait for the action to complete.

Expected behavior

If the action is able to read and manipulate the changelog file, it should be able to commit it back to the repo.

[Ocramius]

Handled in #55