Fixed mixin issues when building the jar file

build.gradle

@@ -6,7 +6,7 @@ buildscript {
     }
     dependencies {
         classpath group: 'net.minecraftforge.gradle', name: 'ForgeGradle', version: '5.+', changing: true
-        classpath 'org.spongepowered:mixingradle:0.7-SNAPSHOT'
+        classpath 'org.spongepowered:mixingradle:0.7.+'
     }
 }
 plugins {
@@ -113,12 +113,16 @@ minecraft {
 apply plugin: 'org.spongepowered.mixin'
 mixin {
     add sourceSets.main, "iceandfire.refmap.json"
+    config 'iceandfire.mixins.json'
 }
 // Include resources generated by data generators.
 sourceSets.main.resources { srcDir 'src/generated/resources' }
 
 dependencies {
+
     minecraft 'net.minecraftforge:forge:1.16.5-36.2.34'
+
+    annotationProcessor 'org.spongepowered:mixin:0.8.5:processor'
     compileOnly fg.deobf("mezz.jei:jei-1.16.2:7.1.3.19:api")
     runtimeOnly fg.deobf("mezz.jei:jei-1.16.2:7.1.3.19")
     implementation "curse.maven:citadel-331936:3441030"