Do not run MySQL tests in parallel

.github/workflows/test.yml

@@ -23,7 +23,7 @@ concurrency:
 # - django 4.2, python 3.9, postgres:12, psycopg 2, parallel
 # - django 4.2, python 3.10, mysql:8.0
 # - django 4.2, python 3.11, mariadb:10.5
-# - django 5.1, python 3.12, mysql:8.4, parallel, USE_EMAIL_USER_MODEL=yes
+# - django 5.1, python 3.12, mysql:8.4, USE_EMAIL_USER_MODEL=yes
 # - django 5.1, python 3.12, mariadb:11.4, USE_EMAIL_USER_MODEL=yes
 # - django 5.1, python 3.13, sqlite, parallel, WAGTAIL_CHECK_TEMPLATE_NUMBER_FORMAT=1
 # - django 5.1, python 3.13, postgres:15, psycopg 3, parallel, DISABLE_TIMEZONE=yes
@@ -197,7 +197,6 @@ jobs:
           - python: '3.12'
             django: 'Django>=5.1,<5.2'
             experimental: false
-            parallel: '--parallel'
             mysql: 'mysql:8.4'
             emailuser: emailuser
     services: