use UTF-8 in MySQL

Author: takano32

docker-compose.yml

@@ -4,6 +4,7 @@ services:
     container_name: mysql
     hostname: mysql
     image: mysql:5.7@sha256:a6ab4c8534bda3415da6a5e7d0edac34722d198880c488ce69e1463be908f700
+    command: mysqld --character-set-server=utf8 --collation-server=utf8_unicode_ci
     ports:
       - 3306:3306
     environment: