fix(Postgres Node): Close connection pool only if it's not already closed or closing (#8690)

packages/nodes-base/nodes/Postgres/v2/actions/router.ts

@@ -58,7 +58,7 @@ export async function router(this: IExecuteFunctions): Promise<INodeExecutionDat
 			sshClient.end();
 		}
 
-		await db.$pool.end();
+		if (!db.$pool.ending) await db.$pool.end();
 	}
 
 	return [returnData];