ci: remove Ruby 3.1 from test matrix

Rails 8.0.2 requires Ruby >= 3.2.0, so we can only test on Ruby 3.2+

Author: vishaltps

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ["3.1", "3.2", "3.3"]
+        ruby-version: ["3.2", "3.3"]
     steps:
       - uses: actions/checkout@v4