update changelog and PollAnswer

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## 9.1.0
 
+**This update contains adding of [Telegram Bot API 6.8](https://core.telegram.org/bots/api-changelog#august-18-2023) support**
+
 * `Version`:
   * `Coroutines`: `1.7.2` -> `1.7.3`
   * `Ktor`: `2.3.2` -> `2.3.3`

tgbotapi.core/src/commonMain/kotlin/dev/inmo/tgbotapi/types/polls/PollAnswer.kt

@@ -10,7 +10,7 @@ import kotlinx.serialization.descriptors.SerialDescriptor
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 
-@Serializable
+@Serializable(PollAnswer.Companion::class)
 sealed interface PollAnswer: FromUser {
     val pollId: PollIdentifier
     override val user: User