fix mysqldump github action

.github/workflows/docker-compose.yml.mysqldbdump

 version: '3'
 services:
   mysql:
-    image: mysql:5.6
-    container_name: edx.devstack.mysql
+    image: mysql:5.7
+    container_name: edx.devstack.mysql57
     ports:
       - '3306:3306'
     environment:
@@ -20,5 +20,4 @@ services:
     volumes:
        - ../../:/edx/app/edxapp/edx-platform
     depends_on:
-      mysql:
-        condition: service_healthy
+      - mysql