add the premium_subscription_count property

src/Discord.Net.Core/Entities/Guilds/IGuild.cs

@@ -231,6 +231,13 @@ namespace Discord
         ///     The description for the guild; <c>null</c> if none is set.
         /// </returns>
         string Description { get; }
+        /// <summary>
+        ///     Gets the number of premium subscribers of this guild.
+        /// </summary>
+        /// <returns>
+        ///     The number of premium subscribers of this guild.
+        /// </returns>
+        int PremiumSubscriptionCount { get; }
 
         /// <summary>
         ///     Modifies this guild.

src/Discord.Net.Rest/API/Common/Guild.cs

@@ -54,5 +54,7 @@ namespace Discord.API
         // this value is inverted, flags set will turn OFF features
         [JsonProperty("system_channel_flags")]
         public SystemChannelMessageDeny SystemChannelFlags { get; set; }
+        [JsonProperty("premium_subscription_count")]
+        public Optional<int> PremiumSubscriptionCount { get; set; }
     }
 }

src/Discord.Net.Rest/Entities/Guilds/RestGuild.cs

@@ -60,6 +60,8 @@ namespace Discord.Rest
         public SystemChannelMessageDeny SystemChannelFlags { get; private set; }
         /// <inheritdoc />
         public string Description { get; private set; }
+        /// <inheritdoc />
+        public int PremiumSubscriptionCount { get; private set; }
 
         /// <inheritdoc />
         public DateTimeOffset CreatedAt => SnowflakeUtils.FromSnowflake(Id);
@@ -118,6 +120,7 @@ namespace Discord.Rest
             VanityId = model.VanityURLCode;
             SystemChannelFlags = model.SystemChannelFlags;
             Description = model.Description;
+            PremiumSubscriptionCount = model.PremiumSubscriptionCount.GetValueOrDefault();
 
             if (model.Emojis != null)
             {

src/Discord.Net.WebSocket/Entities/Guilds/SocketGuild.cs

@@ -101,6 +101,8 @@ namespace Discord.WebSocket
         public SystemChannelMessageDeny SystemChannelFlags { get; private set; }
         /// <inheritdoc />
         public string Description { get; private set; }
+        /// <inheritdoc />
+        public int PremiumSubscriptionCount { get; private set; }
 
         /// <inheritdoc />
         public DateTimeOffset CreatedAt => SnowflakeUtils.FromSnowflake(Id);
@@ -368,6 +370,7 @@ namespace Discord.WebSocket
             VanityId = model.VanityURLCode;
             SystemChannelFlags = model.SystemChannelFlags;
             Description = model.Description;
+            PremiumSubscriptionCount = model.PremiumSubscriptionCount.GetValueOrDefault();
 
             if (model.Emojis != null)
             {