feature: Bump API version to 9 (#1847)

* First changes to the config

* Lots of changes to fit the new version

* Remove PermissionTargetConverter

src/Discord.Net.WebSocket/API/Gateway/IdentifyParams.cs

@@ -17,8 +17,6 @@ namespace Discord.API.Gateway
         public Optional<int[]> ShardingParams { get; set; }
         [JsonProperty("presence")]
         public Optional<StatusUpdateParams> Presence { get; set; }
-        [JsonProperty("guild_subscriptions")]
-        public Optional<bool> GuildSubscriptions { get; set; }
         [JsonProperty("intents")]
         public Optional<int> Intents { get; set; }
     }