chore!: add dialetic env to database config file

backend/.env.example

@@ -4,6 +4,7 @@ FRONTEND_URL=http://localhost:3000
 PROXY_PORT=8080
 PORT=8080
 
+DB_DIALECT=
 DB_HOST=
 DB_USER=
 DB_PASS=

backend/src/config/database.ts

@@ -5,7 +5,7 @@ module.exports = {
     charset: "utf8mb4",
     collate: "utf8mb4_bin"
   },
-  dialect: "mysql",
+  dialect: process.env.DB_DIALECT,
   timezone: "-03:00",
   host: process.env.DB_HOST,
   database: process.env.DB_NAME,