Fix error on @ everyone

Myriad/Rest/Types/AllowedMentions.cs

@@ -1,9 +1,12 @@
-using System.Collections.Generic;
+using System.Text.Json.Serialization;
+
+using Myriad.Serialization;
 
 namespace Myriad.Rest.Types
 {
     public record AllowedMentions
     {
+        [JsonConverter(typeof(JsonSnakeCaseStringEnumConverter))]
         public enum ParseType
         {
             Roles,

Myriad/Serialization/JsonSnakeCaseStringEnumConverter.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Myriad.Serialization
+{
+    public class JsonSnakeCaseStringEnumConverter: JsonConverterFactory
+    {
+        private readonly JsonStringEnumConverter _inner = new(new JsonSnakeCaseNamingPolicy());
+
+        public override bool CanConvert(Type typeToConvert) =>
+            _inner.CanConvert(typeToConvert);
+
+        public override JsonConverter? CreateConverter(Type typeToConvert, JsonSerializerOptions options) =>
+            _inner.CreateConverter(typeToConvert, options);
+    }
+}

PluralKit.Bot/Services/WebhookExecutorService.cs

@@ -83,7 +83,10 @@ namespace PluralKit.Bot
 
             var allowedMentions = content.ParseMentions();
             if (!req.AllowEveryone)
-                allowedMentions = allowedMentions.RemoveUnmentionableRoles(guild);
+                allowedMentions = allowedMentions.RemoveUnmentionableRoles(guild) with {
+                    // also clear @everyones
+                    Parse = Array.Empty<AllowedMentions.ParseType>()
+                };
 
             var webhookReq = new ExecuteWebhookRequest
             {