ci: loop versions in bash shell

Author: toshimaru

.github/workflows/ci.yml

@@ -62,7 +62,7 @@ jobs:
       - name: fetch Rails tags
         working-directory: rails
         run: |
-          for version in v8 v7 v6 v5.2; do
+          for version in $(echo "${{ matrix.build-rails-versions }}" | tr ',' ' ');; do
             git fetch --depth=1 origin refs/tags/${version}*:refs/tags/${version}*
           done
       - uses: ruby/setup-ruby@v1