Drop Ruby 2.6 and 2.7 and add 3.1, 3.2. and 3.3.

Author: ppostma

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.6', '2.7', '3.0']
+        ruby-version: ['3.0', '3.1', '3.2', '3.3']
 
     services:
       postgres: