style(docker-compose.yml): use single quotes.

No code changes.

[ci skip]

Author: php-coder

docker/docker-compose.yml

@@ -4,6 +4,6 @@ services:
   web:
     image: phpcoder/mystamps:latest
     cap_drop:
-      - "ALL"
+      - 'ALL'
     ports:
-      - "8080:8080"
+      - '8080:8080'

docker/prod.yml

@@ -34,7 +34,7 @@ services:
       # the user specified above will be granted superuser access automatically
       - MYSQL_DATABASE=mystamps
     ports:
-      - "3306:3306"
+      - '3306:3306'
     # only for testing locally
     #volumes:
     #  - ./mysql_backup_mystamps_20180901-003001.sql.gz:/docker-entrypoint-initdb.d/dump.sql.gz:ro