Port multiloader build to Fabric and Forge 1.20.1

fabric/gradle.properties

@@ -0,0 +1 @@
+loom.platform=fabric

fabric/src/main/resources/fabric.mod.json

@@ -13,9 +13,9 @@
   "mixins": ["skinsg.mixins.json"],
   "depends": {
     "fabricloader": ">=0.16",
-    "minecraft": "~1.21.1",
-    "java": ">=21",
+    "minecraft": "~1.20.1",
+    "java": ">=17",
     "fabric-api": "*",
-    "architectury": ">=13.0.8"
+    "architectury": ">=9.2.14"
   }
 }