fix: recursive iteration on the local directory

Author: lfoppiano

src/main/java/org/commoncrawl/whirlwind/Duck.java

@@ -154,7 +154,7 @@ private static List<String> getLocalParquetFiles(Path indexPath) throws IOExcept
 			System.exit(1);
 		}
 
-		List<String> files = Files.list(indexPath).filter(p -> p.toString().endsWith(".parquet")).map(Path::toString)
+		List<String> files = Files.walk(indexPath).map(Path::toString).filter(string -> string.endsWith(".parquet"))
 				.collect(Collectors.toList());
 
 		if (files.isEmpty()) {