fix(bot): i need to test my code properly before pushing it

PluralKit.Core/Models/PKMember.cs

@@ -50,7 +50,7 @@ public class PKMember
     public bool KeepProxy { get; private set; }
     public Instant Created { get; private set; }
     public int MessageCount { get; private set; }
-    public Instant? LastMessageTimestamp { get; }
+    public Instant? LastMessageTimestamp { get; private set; }
     public bool AllowAutoproxy { get; private set; }
 
     public PrivacyLevel MemberVisibility { get; private set; }