package/network-manager: bump to version 1.21.2

per upstream commit: e9f2ea6c22f36cb7986d2228763629ed44b9e76b
https://github.com/NetworkManager/NetworkManager/commit/e9f2ea6c22f36cb7986d2228763629ed44b9e76b



The update to the GPL text in COPYRIGHT is purely cosmetic.

Added COPYING.LGPL to licenses for libnm.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>