Revert "(fix): Add explicit separator to implode for PHPStan type safety"

This reverts commit afc00ba.

Author: abnegate

src/Database/Database.php

@@ -9207,7 +9207,7 @@ public function getCacheKeys(string $collectionId, ?string $documentId = null, a
             $documentKey = $documentHashKey = "{$collectionKey}:{$documentId}";
 
             if (!empty($selects)) {
-                $documentHashKey = $documentKey . ':' . \md5(\implode('', $selects));
+                $documentHashKey = $documentKey . ':' . \md5(\implode($selects));
             }
         }