fix: don't use psql 13 functions

The function GEN_RANDOM_UUID was only introduced to built in postgresql
in version 13, however, the installation guide specifies that version 12
should be sufficient.

packages/backend/migration/1685126322423-remove-favourites.js

@@ -6,7 +6,7 @@ export class removeFavourites1685126322423 {
 			WITH "new_clips" AS (
 				INSERT INTO "clip" ("id", "createdAt", "userId", "name")
 				SELECT
-					RIGHT(GEN_RANDOM_UUID()::text, 10),
+					LEFT(MD5(RANDOM()::text), 10),
 					NOW(),
 					"userId",
 					'⭐'