fixup! fix(AmazonS3#headObject): normalize root cache key

Author: Antreesy

apps/files_external/lib/Lib/Storage/AmazonS3.php

@@ -117,7 +117,7 @@ private function invalidateCache(string $key): void {
 	private function headObject(string $key): array|false {
 		// Normalize only the cache key so callers can keep using the original S3 object key.
 		$cacheKey = match ($key) {
-			'', '.', '/' => '.',
+			'', '.' => '.',
 			default => ltrim($key, '/'),
 		};
 		if (!isset($this->objectCache[$cacheKey])) {