fix PrismaClient constructor: pass empty object (required prisma v7)

backend/src/prisma/prisma.service.ts

@@ -4,7 +4,7 @@ import { PrismaClient } from '@prisma/client';
 @Injectable()
 export class PrismaService extends PrismaClient implements OnModuleInit, OnModuleDestroy {
   constructor() {
-    super({ datasources: { db: { url: process.env.DATABASE_URL } } });
+    super({});
   }
 
   async onModuleInit() {