make fine-grained PATs work as $HOMEBREW_GITHUB_API_TOKEN

[bartekpacia]

fix #16978

regex suggested by @Bo98

I confirmed that this fix works by running brew bump-formula-pr locally with $HOMEBREW_GITHUB_API_TOKEN set to my fine-grained PAT, and it worked:

logs

brew bump-formula-pr \
 --no-audit \
 --no-browse \
 --no-fork \
 --message "scripts 0.5.1" \
 --tag "v0.5.1" \
 --revision "$(git rev-parse HEAD)" \
 --force \
 bartekpacia/homebrew-tools/scripts
==> replace /tag:(\s+")v0.5.0(?=")/ with "tag:\\1v0.5.1\\2"
==> replace "a8de90aae81ac40a479ab65b2298412478acb297" with "6b5ff905e880bcc4002a992c0034dfe6bc525419"
==> Skipping `brew audit`
M	Formula/scripts.rb
Switched to a new branch 'bump-scripts-0.5.1'
[bump-scripts-0.5.1 ed068eb] scripts 0.5.1
 1 file changed, 1 insertion(+), 1 deletion(-)
remote:
remote: Create a pull request for 'bump-scripts-0.5.1' on GitHub by visiting:
remote:      https://github.com/bartekpacia/homebrew-tools/pull/new/bump-scripts-0.5.1
remote:
To https://github.com/bartekpacia/homebrew-tools
 * [new branch]      bump-scripts-0.5.1 -> bump-scripts-0.5.1
branch 'bump-scripts-0.5.1' set up to track 'https://******@github.com/bartekpacia/homebrew-tools/bump-scripts-0.5.1'.
https://github.com/bartekpacia/homebrew-tools/pull/24

I tried to find tests for the file I modified but failed at it.

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

[MikeMcQuaid]

Thanks so much for your first contribution! Without people like you submitting PRs we couldn't run this project. You rock, @bartekpacia!