update myql health check

Author: lastlink

.github/workflows/tests.yaml

@@ -67,6 +67,7 @@ jobs:
           MYSQL_ROOT_PASSWORD: secret
         ports:
         - 3306:3306
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
     steps:
     - name: Checkout Kanboard repo
       uses: actions/checkout@v2