pin ruby version

Author: Step7750

.github/workflows/build.yml

@@ -8,18 +8,19 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     strategy:
       matrix:
-        ruby-version: [2.5, 2.6, 2.7, 3.0]
+        ruby-version: [2.7.2]
 
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby-version }}
+        bundler: '2.2.33'
         bundler-cache: true
 
     - run: bundle exec middleman build