update-keys:
Add SPDX license identifier for GPL-3.0-or-later.

LICENSE:
Add GPL-3.0-or-later license file.

New trusted keys with this commit:

 * bastelfreak
 * orhun
 * rgacogne

Baptiste Jonglez resigned on aur-general.

... and collect...

* revoked signatures for bisson & dreisner
* extended lifetime for jleclanche's key

... and get raster's key including signatures.

Dave Reisner resigned on arch-dev.

Gaetan Bisson resigned on arch-dev-public:
https://lists.archlinux.org/pipermail/arch-dev-public/2020-August/030073.html

... and get kgizdov's new key.

... and get hashworks's key.

We need web of trust to download the master key signatures...
So enable it.

... and get freswa's key.

... and get latest signatures.

... and get latest signatures, including new key for heftig.

... and get latest signatures, including key with extended lifetime
from Filipe Laíns (FFY00).

... and get latest signatures, including key with extended lifetime
from Christian Rebischke (shibumi).

... and get latest signatures, including key with extended lifetime
from Nico Hood.

... and get latest signatures.

Resigned on arch-dev mailing list.

... and get latest signatures, including revokation certificate for
thomas' master key by tpowa.