Get the latest RevitAddinUtility.dll

I was using RevitAddinUtility.dll version 26.0.10.8 when I wrote up this question. Before I hit 'post' I realized I did not have the latest version of Revit 2026. I'm now using RevitAddinUtility.dll version 26.1.0.35, and the ManifestSettings save as expected.

The example code above may be useful to others, so I decided to go ahead and post this as a Q&A.