sherpa/sherpa: Sherpa 4.10.2

Sherpa 4.10.2

This release fixes a regression introduced in Sherpa 4.10.1 related to PSF convolution. As part of the long term PSF rebinning improvements, Sherpa 4.10.1 introduced a check to validate that the data pixel size and the PSF pixel size match. If they don't match, then a warning is issued. The change did not account for an edge error case. Sherpa 4.10.2 solves this problem. The regression introduced a downstream regression in the gammapy project.

Sherpa did not properly catch errors when checking the PSF pixel size matches the image pixel size. This has now been fixed.

There is a potential issue for macOS conda users with python > 3.6 and matplotlib v3.0.1, when pyqt5 is not installed and selected as a matplotlib backend. With this specific combination of platform and dependencies matplotlib can fail to work properly. The issue can be replicated without importing Sherpa, so this is not a Sherpa bug.

Several workarounds exist, the simplest of which are:

* install pyqt5 (`conda install pyqt`).
* downgrade matplotlib to v2 or v3.0.0 (`conda install matplotlib=3.0.0`)