Simplify specifying Django test dependency (#1134)

Author: adamchainz

pyproject.toml

@@ -50,7 +50,6 @@ urls.Repository = "https://github.com/adamchainz/django-mysql"
 [dependency-groups]
 test = [
   "coverage[toml]",
-  "django",
   "django-jsonfield-backport",
   "mariadb-dyncol",
   "mysqlclient>=1.4.3",