pack: add Kotlin for Forge 5.11.0, bump to 0.15.1

Hotfix for 0.15.0: Slice & Dice declares 'kotlinforforge >= 5.8' as a
hard dependency and the server crashed on load without it. Adding KFF
satisfies the dep. 6.9 MB, both sides.

pack/pack.lock.json

@@ -1,7 +1,7 @@
 {
   "$schema": "Brass-and-Sigil pack.lock.json - generated, do not edit by hand unless you know what you are doing",
   "name": "Brass and Sigil",
-  "version": "0.15.0",
+  "version": "0.15.1",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",
@@ -448,6 +448,17 @@
       "sha1": "13d8835813b3851d4818c59ec8f7124e4a826c14",
       "size": 406699,
       "side": "both"
+    },
+    {
+      "source": "modrinth",
+      "slug": "kotlin-for-forge",
+      "versionId": "NrSebcsG",
+      "version": "5.11.0",
+      "path": "mods/kotlinforforge-5.11.0-all.jar",
+      "url": "https://cdn.modrinth.com/data/ordsPcFz/versions/NrSebcsG/kotlinforforge-5.11.0-all.jar",
+      "sha1": "4d83e8a8e8cb06b306d2cea1e903680fe513f1f3",
+      "size": 6869790,
+      "side": "both"
     }
   ],
   "defaultServer": {