pango: 1.43.0 -> 1.44.6, fixes CVE-2019-1010238

Bumping version to incorporate a security fix.

Addresses: https://github.com/NixOS/nixpkgs/issues/70120

Upstream fix:
https://gitlab.gnome.org/GNOME/pango/commit/490f8979a260c16b1df055eab386345da18a2d54

Additional change required to build docs:
https://gitlab.gnome.org/GNOME/pango/commit/71461689b0e34d873018d46bff555475019fbf4a

The dropped patch is already incorporated into the version.