Update Java compatibility level in mixins

Author: Aizistral

forge/src/main/resources/mixins/forge/nochatreports-forge.mixins.json

@@ -2,7 +2,7 @@
   "required": true,
   "minVersion": "0.8",
   "package": "com.aizistral.nochatreports.forge.mixins",
-  "compatibilityLevel": "JAVA_18",
+  "compatibilityLevel": "JAVA_21",
   "mixins": [],
   "client": [
 	"client.MixinClientConnection",

neoforge/src/main/resources/mixins/neoforge/nochatreports-neoforge.mixins.json

@@ -2,7 +2,7 @@
   "required": true,
   "minVersion": "0.8",
   "package": "com.aizistral.nochatreports.neoforge.mixins",
-  "compatibilityLevel": "JAVA_18",
+  "compatibilityLevel": "JAVA_21",
   "mixins": [],
   "client": [
 	"client.MixinClientConnection",

src/main/resources/mixins/common/nochatreports.mixins.json

@@ -2,7 +2,7 @@
   "required": true,
   "minVersion": "0.8",
   "package": "com.aizistral.nochatreports.common.mixins",
-  "compatibilityLevel": "JAVA_18",
+  "compatibilityLevel": "JAVA_21",
   "mixins": [
 	"common.MixinServerStatus",
 	"common.MixinFriendlyByteBuf",

src/main/resources/mixins/fabric/nochatreports-fabric.mixins.json

@@ -2,7 +2,7 @@
   "required": true,
   "minVersion": "0.8",
   "package": "com.aizistral.nochatreports.fabric.mixins",
-  "compatibilityLevel": "JAVA_18",
+  "compatibilityLevel": "JAVA_21",
   "mixins": [
   ],
   "client": [