Do not disable timezone when testing against MySQL

MySQL cannot load timezone-aware fixtures when USE_TZ = False.

.github/workflows/test.yml

@@ -24,8 +24,8 @@ concurrency:
 # - django 4.2, python 3.10, mysql:8.0
 # - django 4.2, python 3.11, mariadb:10.5
 # - django 5.0, python 3.11, sqlite, WAGTAIL_CHECK_TEMPLATE_NUMBER_FORMAT=1
-# - django 5.1, python 3.12, mysql:8.4, parallel, USE_EMAIL_USER_MODEL=yes, DISABLE_TIMEZONE=yes
-# - django 5.1, python 3.12, mariadb:11.4, USE_EMAIL_USER_MODEL=yes, DISABLE_TIMEZONE=yes
+# - django 5.1, python 3.12, mysql:8.4, parallel, USE_EMAIL_USER_MODEL=yes
+# - django 5.1, python 3.12, mariadb:11.4, USE_EMAIL_USER_MODEL=yes
 # - django 5.1, python 3.12, sqlite, parallel, USE_EMAIL_USER_MODEL=yes
 # - django 5.1, python 3.12, postgres:15, psycopg 3, parallel, DISABLE_TIMEZONE=yes
 # - django stable/5.1.x, python 3.11, postgres:15, psycopg 3 (allow failures)
@@ -174,14 +174,12 @@ jobs:
             mysql: 'mariadb:11.4'
             healthcmd: 'mariadb-admin ping'
             emailuser: emailuser
-            notz: notz
           - python: '3.12'
             django: 'Django>=5.1,<5.2'
             experimental: false
             parallel: '--parallel'
             mysql: 'mysql:8.4'
             emailuser: emailuser
-            notz: notz
     services:
       mysql:
         image: ${{ matrix.mysql || 'mysql:8.0' }}