Put the electron package in the right category

[simonv3]

After installing using GDebi, the menu shortcut appeared under the “Autre” (Other) category instead of “Son et Vidéo” (Sound and Video…?) as I would’ve expected. I’m setup with French, Canada as system language.

This is a bit odd because we did set the linux.category to Audio but of course that doesn't mean we set it right.

Originally reported here https://community.resonate.is/t/beam-a-native-app-for-linux-macos-and-windows-testing-please/2909/20

Here's the list of available categories https://specifications.freedesktop.org/menu-spec/latest/apa.html#main-category-registry