Bump version to 5.8.1

Signed-off-by: shedaniel <daniel@shedaniel.me>

gradle.properties

@@ -1,7 +1,7 @@
 org.gradle.jvmargs=-Xmx3G
 org.gradle.daemon=false
 
-mod_version=5.8.0
+mod_version=5.8.1
 minecraft_version=1.16.4
 
 architectury_version=1.5.112