Get rid of mysql strict trans mode warnings

Here, we adopt the same behaviour as edX.org.

See the following links for documentation:
https://docs.djangoproject.com/en/1.11/ref/databases/#mysql-sql-mode
https://dev.mysql.com/doc/refman/en/sql-mode.html#sql-mode-strict

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Note: Breaking changes between versions are indicated by "💥".
 
+## Unreleased
+
+- [Improvement] Enable Mysql strict mode
+
 ## 3.7.1 (2019-10-06)
 
 - [Feature] Introduce tutor docker image

tutor/templates/apps/openedx/config/partials/auth.json

@@ -36,7 +36,10 @@
       "NAME": "{{ OPENEDX_MYSQL_DATABASE }}",
       "USER": "{{ OPENEDX_MYSQL_USERNAME }}",
       "PASSWORD": "{{ OPENEDX_MYSQL_PASSWORD }}",
-      "ATOMIC_REQUESTS": true
+      "ATOMIC_REQUESTS": true,
+      "OPTIONS": {
+          "init_command": "SET sql_mode='STRICT_TRANS_TABLES'"
+      }
     }
   },
   "EMAIL_HOST_USER": "{{ SMTP_USERNAME }}",