workflows: use PAT instead of default GITHUB_TOKEN

Should prevent errors like:

Error: [{"type"=>"FORBIDDEN", "path"=>["repository", "pullRequest", "reviews", "nodes", 0, "author", "email"], "extensions"=>{"saml_failure"=>false}, "locations"=>[{"line"=>6, "column"=>27}], "message"=>"Resource not accessible by integration"}]

https://github.com/Homebrew/homebrew-core/runs/826063506?check_suite_focus=true#step:7:20

.github/workflows/publish-commit-bottles.yml

@@ -55,7 +55,7 @@ jobs:
         uses: Homebrew/actions/git-user-config@master
       - name: Pull bottles
         env:
-          HOMEBREW_GITHUB_API_TOKEN: ${{secrets.GITHUB_TOKEN}}
+          HOMEBREW_GITHUB_API_TOKEN: ${{secrets.HOMEBREW_GITHUB_API_TOKEN}}
           HOMEBREW_BINTRAY_USER: brewtestbot
           HOMEBREW_BINTRAY_KEY: ${{secrets.HOMEBREW_BINTRAY_KEY}}
         run: |