fix(locking): Accept mixed as value on setTTL

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

lib/private/Lock/MemcacheLockingProvider.php

@@ -25,7 +25,7 @@ public function __construct(
 		parent::__construct($ttl);
 	}
 
-	private function setTTL(string $path, ?int $ttl = null, ?int $compare = null): void {
+	private function setTTL(string $path, ?int $ttl = null, mixed $compare = null): void {
 		if (is_null($ttl)) {
 			$ttl = $this->ttl;
 		}