Switch CI test database to MySQL (#1417)

.ci.settings.py

@@ -7,3 +7,17 @@ CACHES = {
         'BACKEND': 'django.core.cache.backends.locmem.LocMemCache'
     }
 }
+
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.mysql',
+        'NAME': 'dmoj',
+        'USER': 'root',
+        'PASSWORD': 'root',
+        'HOST': 'localhost',
+        'PORT': '3306',
+        'OPTIONS': {
+            'charset': 'utf8mb4',
+        },
+    },
+}

.github/workflows/build.yml

@@ -20,5 +20,7 @@ jobs:
         pip install -r requirements.txt
         pip install mysqlclient
         cp .ci.settings.py dmoj/local_settings.py
+    - name: Start MySQL
+      run: sudo systemctl start mysql.service
     - name: Run unit tests
       run: python manage.py test judge