ci: downgrade ruby version

This commit downgrades the ruby verison in the awesome-bot job to the
version that is supported by the
[github-pages gem](github/pages-gem#752 (comment)).

.github/workflows/lint.yaml

@@ -37,7 +37,7 @@ jobs:
       - name: "setup ruby"
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.0.1
+          ruby-version: 2.7.8
           bundler-cache: true
       - name: "install awesome-bot"
         run: gem install awesome_bot