Build correctly for 1.21

gradle.properties

@@ -1,19 +1,16 @@
-# https://github.com/FabricMC/fabric-example-mod/blob/9b028bdcd43190d4f848d5898b89177de6776535/gradle.properties#L1
-
-# Done to increase the memory available to gradle.
+# Done to increase the memory available to Gradle
 org.gradle.jvmargs=-Xmx1G
 org.gradle.parallel=true
 
 # Fabric Properties
-# check these on https://fabricmc.net/develop
-minecraft_version=1.20.4
-yarn_mappings=1.20.4+build.3
-loader_version=0.15.6
+minecraft_version=1.21
+yarn_mappings=1.21+build.9
+loader_version=0.15.11
 
 # Mod Properties
 mod_version = 0.1.2
-maven_group = io.github.twokilohertz.hotbarreplace
+maven_group = xyz.twokilohertz
 archives_base_name = HotbarReplace
 
 # Dependencies
-fabric_version=0.95.1+1.20.4
+fabric_version=0.100.7+1.21