revert --skip-build due to causing missing files

The setup.py uses build logic to build the list of data files to install, so
none of them are installed if --skip-build is used.

Fixes FS#66468 FS#67191

PKGBUILD

@@ -3,7 +3,7 @@
 
 pkgname=gufw
 pkgver=20.04.1
-pkgrel=1
+pkgrel=2
 pkgdesc='Uncomplicated way to manage your Linux firewall'
 url='https://gufw.org/'
 arch=('any')
@@ -30,7 +30,7 @@ package() {
   cd ${pkgname}-${pkgver}
   # required so desktop, icon and translation files get installed
   export XDG_RUNTIME_DIR="/tmp/${pkgname}"
-  python setup.py install --prefix=/usr --root="${pkgdir}" -O1 --skip-build
+  python setup.py install --prefix=/usr --root="${pkgdir}" -O1
 }
 
 # vim: ts=2 sw=2 et: