Bump OmniCore to 0.21.0 to fix packet receiver issues

Author: Deftu

gradle/libs.versions.toml

@@ -21,7 +21,7 @@ copycat-image-awt = "0.1.1"
 
 # Per version
 textile = "0.8.0"
-omnicore = "0.20.0"
+omnicore = "0.21.0"
 lwjgl = "3.3.3" # All downloaded by the isolated-lwjgl3-loader
 
 # Legacy only