prepare release 4.6.0

[cehbrecht]

Overview

This PR prepares the release 4.6.0.

Related Issue / Discussion

Additional Information

Contribution Agreement

(as per https://github.com/geopython/pywps/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to PyWPS. I confirm that my contributions to PyWPS will be compatible with the PyWPS license guidelines at the time of contribution.
• I have already previously agreed to the PyWPS Contributions and Licensing Guidelines

[cehbrecht]

@Zeitsperre @tomkralidis when accepted I will make a new release 4.6.0

[coveralls]

coverage: 84.061%. remained the same
when pulling 8481191 on cehbrecht:prepare-release-4.6.2_2nd-try
into 53b0c81 on geopython:main.

[Zeitsperre]

Hey @cehbrecht! Sorry for the late response (was on a mini-vacation). I will give this a look in the next few hours!

[Zeitsperre]

@cehbrecht If you could add the fix for #678 into here as well as remove the import sys in setup.py, I think we'd be good to merge!