licenses: Update the DUMB license file to version 0.9.3

licenses: Update the DUMB license file to version 0.9.3

The media-libs/dumb, media-libs/aldumb, and games-fps/gzdoom package
were all released under the DUMB 0.9.3 license. Since no existing
Gentoo package is released under the DUMB 0.9.2 license, the DUMB-0.9.2
license file has been replaced with the DUMB-0.9.3 license file.

Package-Manager: Portage-2.3.67, Repoman-2.3.13
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Closes: https://github.com/gentoo/gentoo/pull/12178
Signed-off-by: James Le Cuirot <chewi@gentoo.org>