[postgres] retrive foreign keys in determinist order

this failed on my macos as it returned keys in a different order,
e.g. nextras orm's users_x_users was returning pk foregin keys backwards

src/Platforms/PostgreSqlPlatform.php

@@ -162,7 +162,9 @@ public function getForeignKeys(string $table, ?string $schema = null): array
 			count($tableArgs) > 1
 				? "AND cl.oid = '%table.%table'::regclass"
 				: "AND cl.oid = '%table'::regclass"
-			), ...$tableArgs);
+			) . '
+			ORDER BY atf.attnum
+			', ...$tableArgs);
 
 		$keys = [];
 		foreach ($result as $row) {