Exclude GuidAttribute from WinMD. (#1855)

Co-authored-by: Manodasan Wignarajah <[email protected]>

Author: dongle-the-gadget

src/Authoring/WinRT.SourceGenerator/WinRTTypeWriter.cs

@@ -1696,6 +1696,11 @@ private void AddCustomAttributes(IEnumerable<AttributeData> attributes, EntityHa
                     continue;
                 }
 
+                if (attributeType.ToString() == "System.Runtime.InteropServices.GuidAttribute")
+                {
+                    continue;
+                }
+
                 // Skip the [GeneratedBindableCustomProperty] attribute. It is valid to add this on types in WinRT
                 // components (if they need to be exposed and implement ICustomPropertyProvider), but the attribute
                 // should never show up in the .winmd file (it would also cause build errors in the projections).