Test against real dj5.1 release

.github/workflows/ci.yml

@@ -56,7 +56,7 @@ jobs:
       matrix:
         # https://docs.djangoproject.com/en/5.1/faq/install/#what-python-version-can-i-use-with-django
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
-        django-version: ["4.2", "5.0", "5.1b1"]
+        django-version: ["4.2", "5.0", "5.1"]
         db-engine: [sqlite, postgres]
         tz-engine: [pytz, zoneinfo]
         exclude:
@@ -66,11 +66,11 @@ jobs:
             python-version: "3.9"
           - django-version: "5.0"
             tz-engine: pytz
-          - django-version: "5.1b1"
+          - django-version: "5.1"
             python-version: "3.8"
-          - django-version: "5.1b1"
+          - django-version: "5.1"
             python-version: "3.9"
-          - django-version: "5.1b1"
+          - django-version: "5.1"
             tz-engine: pytz
 
     env: