Mysql: set default charset to utf8mb4

src/db/MysqlConnectionManager.ts

@@ -47,6 +47,7 @@ export default class MysqlConnectionManager {
                 host: config.get('mysql.host'),
                 user: config.get('mysql.user'),
                 password: config.get('mysql.password'),
+                charset: 'utf8mb4',
             });
             await new Promise((resolve, reject) => {
                 connection.query(`CREATE DATABASE IF NOT EXISTS ${dbName}`, (error) => {