Fix GitHub actions and add comments table (#1604)

* Fix MySQL and Postgres GitHub actions to properly test databases
* Add migration to add `comments` table

.github/workflows/mysql.yml

@@ -9,13 +9,16 @@ jobs:
     runs-on: ubuntu-latest
     services:
       mysql:
-        image: mysql
+        image: mysql:5.7
+        env:
+          MYSQL_ROOT_PASSWORD: password
         ports:
           - 3306
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
       redis:
         image: redis
         ports:
-          - 6379
+          - 6379:6379
 
     strategy:
       matrix:
@@ -42,7 +45,7 @@ jobs:
         env:
             AWS_ACCESS_KEY_ID: AKIAIOSFODNN7EXAMPLE
             AWS_SECRET_ACCESS_KEY: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
-            TESTING_DATABASE_URL: mysql+pymysql://root@mysql/ctfd
+            TESTING_DATABASE_URL: mysql+pymysql://root:password@localhost:${{ job.services.mysql.ports[3306] }}/ctfd
 
       - name: Codecov
         uses: codecov/codecov-action@v1.0.11