Remove unneded mixin for iris (Iris now has 32 render targets by default)

Author: MCRcortex

src/main/java/me/cortex/voxy/client/mixin/iris/MixinPackRenderTargetDirectives.java

@@ -12,7 +12,6 @@
     "iris.MixinIrisSamplers",
     "iris.MixinLevelRenderer",
     "iris.MixinMatrixUniforms",
-    "iris.MixinPackRenderTargetDirectives",
     "iris.MixinProgramSet",
     "iris.MixinShaderPackSourceNames",
     "iris.MixinStandardMacros",