refactor: refactored gql-user-decorator to work for subscriptions

packages/hoppscotch-backend/src/decorators/gql-user.decorator.ts

@@ -4,7 +4,7 @@ import { GqlExecutionContext } from '@nestjs/graphql';
 export const GqlUser = createParamDecorator(
   (data: unknown, context: ExecutionContext) => {
     const ctx = GqlExecutionContext.create(context);
-    return ctx.getContext().req.user;
+    const { req, headers } = ctx.getContext();
+    return headers ? headers.user : req.user;
   },
 );
-