Fix channel checks missing GuildNews

The log channel / logclean checks are left as-is; hopefully nobody is
using an announcements channel for their logs?

PluralKit.Bot/Handlers/ReactionAdded.cs

@@ -66,8 +66,8 @@ namespace PluralKit.Bot
                 }
             }
 
-            // Only proxies in guild text channels
-            if (channel.Type != Channel.ChannelType.GuildText) return;
+            // Proxied messages only exist in guild text channels, so skip checking if we're elsewhere
+            if (DiscordUtils.IsValidGuildChannel(channel)) return;
 
             // Ignore reactions from bots (we can't DM them anyway)
             if (user.Bot) return;