ci-scripts 2.3.0 available: Windows builds on AppVeyor

[Ralph Lange via Tech-talk <tech-talk at aps.anl.gov>]

ci-scripts 2.3.0 features support for native Windows builds using the AppVeyor service:

• use different compilers (Visual Studio, MinGW)
• use different VS versions (2008, 2010, 2012, 2013, 2015, 2017, 2019)
• compile for Windows 32bit and 64bit
• create static libraries or DLLs (plus the matching executables)
• create optimized or debug builds.

This is a minor release, i.e. existing Travis-CI configuration does not need to be changed.

Thanks a lot to everyone who contributed and helped, most prominently Michael Davidsaver and Freddie Akeroyd.

Cheers,
~Ralph