Making Mullvad Browser the default on Windows 10/11 doesn't work

This was fixed in #80 (closed), but now it's not working anymore.

The current behavior in Firefox 115 ESR/ Firefox 126 is that clicking "Make default" (either in the popup if you have ticked Always check if ${browser} is your default browser or by clicking on the button in the settings) should open the Default Apps, where the user can manually set the browser as the default.

With latest Mullvad Browser Nightly (https://nightlies.tbb.torproject.org/nightly-builds/tor-browser-builds/tbb-nightly.2024.05.30/mullvadbrowser-nightly-windows-x86_64/ as of now), the notification request for pinning shows, but not the Default Apps window and its corresponding notification.