Manifest permissions

[Tiagoquix]

Hi there. It seems some more permissions and env. variables have been added/removed over time to the Steam Flatpak. Could you take a look at their manifest to see if you can include/remove new permissions from the Protontricks Flatpak too?

https://github.com/flathub/com.valvesoftware.Steam/blob/beta/com.valvesoftware.Steam.yml (Beta branch I believe)
https://github.com/flathub/com.valvesoftware.Steam/blob/master/com.valvesoftware.Steam.yml (master/stable branch)

And also, something I want to highlight: the network manager permission is not used by them by default. See https://github.com/flathub/com.valvesoftware.Steam/wiki#app-starts-slower-than-native.

Thanks in advance.