system-config-printer: update hash to really upgrade to 1.5.7

Commit 03353ce6 ("system-config-printer: 1.3.12 -> 1 5.7")
forgot to update the hash. So since that commit we actually continued to
use the old version (1.3.12) because of the NixOS tarball cache...

The new version prints some warnings on startup:

  /nix/store/HASH-system-config-printer-1.5.7/share/system-config-printer/system-config-printer.py:32: \
    PyGIWarning: Polkit was imported without specifying a version first. \
    Use gi.require_version('Polkit', '1.0') before import to ensure that the right version gets loaded.
  from gi.repository import Polkit

...and similar errors for GdkPixbuf, Gdk, Gtk and Notify. These warnings
are already fixed upstream and will be part of the next release.

Implementation details:
* The new version needs python3.
* Remove unneeded, and python3 incompatible, 'notify' dependency.
  system-config-printer > 1.3.12 replaced it with GOBject introspection
  bindings to libnotify (from gi.repository import Notify).
* Add gtk3, gdk_pixbuf, pango, atk, libnotify as needed (for gobject
  introspection).
* A new --with-udevdir configure option is used to prevent the
  installer from trying to install stuff to "/rules.d" (yes, the root).
* Get pycups from the passed pythonPackages set (fixes loading of
  python cups module).
* Use pygobject3 instead of pygobject, as needed.
* Use dbus from the passed pythonPackages attrset instead of
  pythonDBus, so we get a python3 compatible module that loads
  successfully.
* Python requests2 modules is required.