Remove redundant GetCategoryAsync methods from socket entities

src/Discord.Net.WebSocket/Entities/Channels/SocketTextChannel.cs

@@ -124,10 +124,6 @@ namespace Discord.WebSocket
         public Task<IReadOnlyCollection<RestWebhook>> GetWebhooksAsync(RequestOptions options = null)
             => ChannelHelper.GetWebhooksAsync(this, Discord, options);
 
-        // Categories
-        public Task<ICategoryChannel> GetCategoryAsync(RequestOptions options = null)
-            => ChannelHelper.GetCategoryAsync(this, Discord, options);
-
         private string DebuggerDisplay => $"{Name} ({Id}, Text)";
         internal new SocketTextChannel Clone() => MemberwiseClone() as SocketTextChannel;
 

src/Discord.Net.WebSocket/Entities/Channels/SocketVoiceChannel.cs

@@ -56,9 +56,6 @@ namespace Discord.WebSocket
             return null;
         }
 
-        public Task<ICategoryChannel> GetCategoryAsync(RequestOptions options = null)
-            => ChannelHelper.GetCategoryAsync(this, Discord, options);
-
         private string DebuggerDisplay => $"{Name} ({Id}, Voice)";
         internal new SocketVoiceChannel Clone() => MemberwiseClone() as SocketVoiceChannel;