chore: Pin django-stubs to working version (ietf-tools#6503)

Author: jennifer-richards

requirements.txt

@@ -22,7 +22,8 @@ django-markup>=1.5    # Limited use - need to reconcile against direct use of ma
 django-oidc-provider>=0.8    # 0.8 dropped Django 2 support
 django-referrer-policy>=1.0
 django-simple-history>=3.0.0
-django-stubs>=4.2.0    # The django-stubs version used determines the the mypy version indicated below
+#django-stubs>=4.2.0    # The django-stubs version used determines the the mypy version indicated below
+django-stubs==4.2.4    # Pin here until we fix test failures (and update mypy version, too)
 django-tastypie>=0.14.5    # Version must be locked in sync with version of Django
 django-vite>=2.0.2
 django-webtest>=1.9.10    # Only used in tests