fix did file

Author: mraszyk

spec/_attachments/ic.did

@@ -126,9 +126,9 @@ service ic : {
   upload_chunk : (record {
     canister_id : principal;
     chunk : blob;
-  }) -> chunk_hash;
-  stored_chunks: (record {canister_id : canister_id}) -> vec chunk_hash;
-  delete_chunks: (record {canister_id : canister_id, hash_list : vec chunk_hash}) -> ();
+  }) -> (chunk_hash);
+  stored_chunks: (record {canister_id : canister_id}) -> (vec chunk_hash);
+  delete_chunks: (record {canister_id : canister_id; hash_list : vec chunk_hash}) -> ();
   clear_chunk_store: (record {canister_id: canister_id}) -> ();
   install_code : (record {
     mode : variant {install; reinstall; upgrade};