Remove 2.7 due to dependency and add modern ruby 3.3

Author: zachaysan

.github/workflows/pull_request.yaml

@@ -31,7 +31,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.7', '3.0', '3.1', '3.2']
+        ruby-version: ['3.0', '3.1', '3.2', '3.3']
 
     steps:
     - uses: actions/checkout@v3