Add Ruby 3.3 to the build matrix

Author: sikachu

.github/workflows/tests.yml

@@ -86,6 +86,17 @@ jobs:
           - ruby: "3.2"
             rails: edge
 
+          - ruby: "3.3"
+            rails: ~> 6.0.0
+          - ruby: "3.3"
+            rails: ~> 6.1.0
+          - ruby: "3.3"
+            rails: ~> 7.0.0
+          - ruby: "3.3"
+            rails: ~> 7.1.0
+          - ruby: "3.3"
+            rails: edge
+
           - ruby: head
             rails: ~> 7.1.0
           - ruby: head