ci: Add ruby 3.0 tests

Author: tonobo

.github/workflows/test.yaml

@@ -35,7 +35,7 @@ jobs:
       matrix:
         os: ["ubuntu-latest"]
         redis: ["6.0"]
-        ruby: ["2.7", "2.6", "2.5", "2.4"]
+        ruby: ["3.0", "2.7", "2.6", "2.5", "2.4"]
         driver: ["ruby", "hiredis", "synchrony"]
     runs-on: ${{ matrix.os }}
     env: