Change GetMethod for SetMethod in ReflectionUtils

Should be checking against setters, not getters

src/Discord.Net.Commands/Utilities/ReflectionUtils.cs

@@ -58,7 +58,7 @@ namespace Discord.Commands
             {
                 foreach (var prop in ownerType.DeclaredProperties)
                 {
-                    if (prop.GetMethod?.IsStatic == false && prop.SetMethod?.IsPublic == true && prop.GetCustomAttribute<DontInjectAttribute>() == null)
+                    if (prop.SetMethod?.IsStatic == false && prop.SetMethod?.IsPublic == true && prop.GetCustomAttribute<DontInjectAttribute>() == null)
                         result.Add(prop);
                 }
                 ownerType = ownerType.BaseType.GetTypeInfo();