fix: fixed error when trying to write metadata in downloader

Author: quintesse

src/main/java/dev/jbang/jdkdb/util/MetadataUtils.java

@@ -189,7 +189,7 @@ private interface AlphabeticPropertyOrder {}
 
 	public static JdkMetadata readMetadataFile(Path metadataFile) throws IOException {
 		JdkMetadata md = readMapper.readValue(metadataFile.toFile(), JdkMetadata.class);
-		md.metadataFile(metadataFile);
+		md.metadataFile(metadataFile.toAbsolutePath());
 		return md;
 	}