Remove legacy/minor Rubies from CI for now.

Author: simi

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.7, '3.0', '3.1', '3.2']
+        ruby: ['3.1', '3.2', '3.3', '3.4']
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3