Drop 1.16.5 support to use Mojang mappings

Because there is no option to create a `remapped-mojang` artifact for 1.16.5 and the whole point of the scripts is to save me time, 1.16.5 support is being removed earlier than usual.

Also fixes issues with NMS-based shulker collision check.
Closes #36

plugin/src/main/java/com/lishid/openinv/util/InternalAccessor.java

@@ -83,6 +83,8 @@ public class InternalAccessor {
             case "v1_16_R2":
                 return "https://github.com/lishid/OpenInv/releases/tag/4.1.5";
             case "v1_16_R3":
+                return "https://github.com/Jikoo/OpenInv/releases/tag/4.1.8";
+            case "v1_17_R1":
             default:
                 return "https://github.com/Jikoo/OpenInv/releases";
         }