Remove now-redundant opt-in on ExperimentalSerializationApi

JsonUnquotedLiteral has now been stabilized in kotlinx.serialization:
https://github.com/Kotlin/kotlinx.serialization/releases/tag/v1.10.0

Author: hermannm

src/commonMain/kotlin/dev/hermannm/devlog/LogField.kt

@@ -5,7 +5,6 @@ package dev.hermannm.devlog
 
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
-import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.SerializationStrategy
@@ -355,9 +354,6 @@ internal object RawJsonSerializer : KSerializer<RawJson> {
   override val descriptor: SerialDescriptor
     get() = primitiveSerializer.descriptor
 
-  // `JsonUnquotedLiteral` is experimental, but will likely be stabilized as-is:
-  // https://github.com/Kotlin/kotlinx.serialization/issues/2900
-  @OptIn(ExperimentalSerializationApi::class)
   override fun serialize(encoder: Encoder, value: RawJson) {
     when (value) {
       is ValidRawJson -> {