Update CI workflow

Author: kmcphillips

.github/workflows/main.yml

@@ -9,22 +9,12 @@ jobs:
       fail-fast: true
       matrix:
         ruby-version:
-          - 2.6
-          - 2.7
-          - 3.0.0
-          - 3.1
+          - 3.3
         gemfile:
-          - rails5_2.gemfile
-          - rails6_0.gemfile
-          - rails6_1.gemfile
           - rails7_0.gemfile
-        exclude:
-          - ruby-version: 2.6
-            gemfile: rails7_0.gemfile
-          - ruby-version: 3.0.0
-            gemfile: rails5_2.gemfile
-          - ruby-version: 3.1
-            gemfile: rails5_2.gemfile
+        # exclude:
+        #   - ruby-version: 2.6
+        #     gemfile: rails7_0.gemfile
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2