Avoid using MATZBOT_GITHUB_TOKEN for pull requests

Author: k0kubun

.github/workflows/check_misc.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
         with:
-          token: ${{ secrets.MATZBOT_GITHUB_TOKEN }}
+          token: ${{ (github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull')) && secrets.MATZBOT_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
 
       - uses: ./.github/actions/setup/directories
         with: