confirm support for CockroachDB 25.3

Author: timgraham

.github/workflows/tests.yml

@@ -54,6 +54,11 @@ jobs:
             use_psycopg2: psycopg2
           - crdb-version: v25.2.0
             use_server_side_binding: server_side_binding
+          - crdb-version: v25.3.0-alpha.3
+          - crdb-version: v25.2.0-alpha.3
+            use_psycopg2: psycopg2
+          - crdb-version: v25.2.0-alpha.3
+            use_server_side_binding: server_side_binding
           # Uncomment to enable testing of CockroachDB nightly.
           #- crdb-version: LATEST
           #- crdb-version: LATEST