Only find service files in the base META-INF/services/ folder. (#4)

Author: Yeregorix

src/main/java/cpw/mods/jarhandling/impl/Jar.java

@@ -282,7 +282,7 @@ private List<Provider> gatherProviders(BiPredicate<String, String> filter) {
             return List.of();
 
         try {
-            return Files.walk(services)
+            return Files.list(services)
                 .filter(Files::isRegularFile)
                 .map(path -> getProvider(path, filter))
                 .toList();