Fix source download

The homepage of gpm is gone, the source is hosted on our own server now.

PKGBUILD

@@ -9,7 +9,7 @@ url="http://www.nico.schottelius.org/software/gpm/"
 license=('GPL')
 depends=('bash' 'procps-ng')
 options=('!makeflags')
-source=(http://www.nico.schottelius.org/software/gpm/archives/${pkgname}-${pkgver}.tar.lzma
+source=(https://sources.archlinux.org/other/gpm/${pkgname}-${pkgver}.tar.lzma
         gpm.sh gpm.service)
 sha1sums=('8d9f3655c80ce7667d31ede2a100b44986480369'
           '94447c6f8bfadd062efa1a747a597426f339d13e'