Add testing against MySQL / Django 4.1.x

.github/workflows/test.yml

@@ -27,6 +27,7 @@ concurrency:
 # - django 4.0, python 3.10, postgres, USE_EMAIL_USER_MODEL=yes
 # - django 4.1, python 3.10, postgres, DISABLE_TIMEZONE=yes
 # - django stable/4.1.x, python 3.10, postgres (allow failures)
+# - django stable/4.1.x, python 3.10, mysql (allow failures)
 # - django main, python 3.10, postgres (allow failures)
 # - elasticsearch 5, django 3.2, python 3.7, sqlite
 # - elasticsearch 6, django 3.2, python 3.7, postgres
@@ -131,6 +132,9 @@ jobs:
           - python: '3.9'
             django: 'Django>=4.1,<4.2'
             experimental: false
+          - python: '3.10'
+            django: 'git+https://github.com/django/django.git@stable/4.1.x#egg=Django'
+            experimental: true
 
     services:
       mysql: