use database connection pool

src/db/database.ts

@@ -127,12 +127,12 @@ export class Database {
   }
 
   static async init(databaseUri: string) {
-    const connection = await mysql.createConnection({
+    const connectionPool = mysql.createPool({
       uri: databaseUri
     });
 
     const db = drizzle({
-      client: connection,
+      client: connectionPool,
       schema: {
         admin,
         team,