fix: Add Kotlin serialization plugin to resolve compilation errors

build.gradle

···
 	id 'net.fabricmc.fabric-loom-remap' version "${loom_version}"
 	id 'maven-publish'
 	id "org.jetbrains.kotlin.jvm" version "2.3.0"
+	id "org.jetbrains.kotlin.plugin.serialization" version "2.3.0"
 }
 
 version = project.mod_version

src/main/kotlin/com/jollywhoppers/atproto/examples/RecordCreationExample.kt

···
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.encodeToJsonElement
 import java.util.*
 
 /**
···
         val requestBody = CreateRecordRequest(
             repo = session.did,
             collection = "com.jollywhoppers.minecraft.player.stats",
-            record = record
+            record = json.encodeToJsonElement(record)
         )
 
         val response = sessionManager.makeAuthenticatedRequest(
···
             repo = session.did,
             collection = "com.jollywhoppers.minecraft.player.profile",
             rkey = "self",
-            record = record
+            record = json.encodeToJsonElement(record)
         )
 
         sessionManager.makeAuthenticatedRequest(
···
         val requestBody = CreateRecordRequest(
             repo = session.did,
             collection = "com.jollywhoppers.minecraft.achievement",
-            record = record
+            record = json.encodeToJsonElement(record)
         )
 
         sessionManager.makeAuthenticatedRequest(
···
     data class CreateRecordRequest(
         val repo: String,
         val collection: String,
-        val record: Any
+        val record: JsonElement
     )
 
     @Serializable
···
         val repo: String,
         val collection: String,
         val rkey: String,
-        val record: Any
+        val record: JsonElement
     )
 }