Drop Ruby <= 3.0 for rails main

Author: JonRowe

.github/workflows/ci.yml

@@ -43,12 +43,6 @@ jobs:
          - ruby: 3.1
            env:
              RAILS_VERSION: 'main'
-         - ruby: '3.0'
-           env:
-             RAILS_VERSION: 'main'
-         - ruby: 2.7
-           env:
-             RAILS_VERSION: 'main'
 
          # Rails 7.1 builds >= 2.7
          - ruby: 3.2