Import createClient in collaborators route

Added the import of createClient from @/lib/database in the project collaborators API route. This prepares the file for potential usage of createClient.

Author: DongDuong2001

app/api/projects/[id]/collaborators/route.ts

@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server"
 import { createServerSupabaseClient } from "@/lib/database/supabase-server"
-import { getProjectCollaborators, removeProjectCollaborator } from "@/lib/database"
+import { createClient, getProjectCollaborators, removeProjectCollaborator } from "@/lib/database"
 
 // GET /api/projects/[id]/collaborators - List collaborators for a project
 export async function GET(