deps: update dependency django to v6

Author: renovate[bot]

pyproject.toml

@@ -8,7 +8,7 @@ optional-dependencies = { test-tools = [
     "pyfakefs (>=5,<6)",
     "pytest-django (>=4,<5)",
 ], common-core = [
-    "django (>4,<6)",
+    "django (>6,<7)",
     "django-health-check",
     "djangorestframework-recursive",
     "djangorestframework",
@@ -22,7 +22,7 @@ optional-dependencies = { test-tools = [
     "simplejson (>=3,<4)",
 ], task-processor = [
     "backoff (>=2.2.1,<3.0.0)",
-    "django (>4,<6)",
+    "django (>6,<7)",
     "django-health-check",
     "prometheus-client (>=0.0.16)",
 ], flagsmith-schemas = [