- Require Pillow
- Bump dependency versions

- Work on unit testing
* Move architecture selection to bcond definition at top of
specfile. This makes it clear in the OBS web UI that the test
flavor is only built for x86_64 and aarch64
* do not build everything a second time during check (in-place)
* instead use new subpackage testdata wich contains the baseline
images created at regular build time
* use pytest-xvfb and %pytest macro
(buildroot path actually not required)
* tidy test skip definitions
* add python-gobject-Gdk to pass the gtk3 backend testso
- include version for obsoletes -qt-shared (rpmlint warning)
- move some cairo files to backend packages
- remove python2 transition requirements mock and six
- update matplotlib-setup.cfg

- update to version 3.3.0
+ Figure and Axes creation / management
* Provisional API for composing semantic axes layouts from text or nested lists
* GridSpec.subplots()
* New Axes.sharex, Axes.sharey methods
* tight_layout now supports suptitle
* Setting axes box aspect
+ Colors and colormaps
* Turbo colormap
* colors.BoundaryNorm supports extend keyword argument
* Text color for legend labels