gnome-common: Version drop to 3.6.0, latest x.{even} version

Signed-off-by: Kieran Ramos <ramos.kieran@gmail.com>
py3cairo: Add formula for py3cairo 1.10.0. This seems necessary as `pip3 install pycairo` failed to install. The name py3cairo matches what Debian uses but disagrees with the developers calling it pycairo; however, the pygobject and other projects look for py3cairo.

Signed-off-by: Kieran Ramos <ramos.kieran@gmail.com>