Fix #111

Signed-off-by: shedaniel <daniel@shedaniel.me>

fabric/src/main/java/me/shedaniel/architectury/hooks/fabric/PackRepositoryHooksImpl.java

@@ -19,17 +19,17 @@
 
 package me.shedaniel.architectury.hooks.fabric;
 
-import com.google.common.collect.ImmutableSet;
 import net.minecraft.server.packs.repository.PackRepository;
 import net.minecraft.server.packs.repository.RepositorySource;
 
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 
 public class PackRepositoryHooksImpl {
     public static void addSource(PackRepository repository, RepositorySource source) {
         List<RepositorySource> set = new ArrayList<>(repository.sources);
         set.add(source);
-        repository.sources = ImmutableSet.copyOf(set);
+        repository.sources = new HashSet<>(set);
     }
 }