[3.20] community/networkmanager: upgrade to 1.46.6

• switch tarball source to gitlab.freedesktop.org, not available on gnome server, see https://download.gnome.org/sources/NetworkManager/1.46/

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https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/compare/1.46.2...1.46.6

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/c6226cde087fb77911749148f50e927f22f78c9c/NEWS