fix: correct cache busting syntax in migration

Author: nzxl101

root/app/www/public/migrations/007_redactions.php

@@ -44,4 +44,4 @@
 }
 
 //-- NEEDED SINCE WE ADD A NEW FIELD TO THIS TABLE
-$proxyDb->$cache->bust(APPS_TABLE_CACHE_KEY);
+$proxyDb->cache->bust(APPS_TABLE_CACHE_KEY);