Numpy and Scipy deprecation warnings fixed

[fjosw]

This PR fixes two deprecation warnings.

[fjosw]

The Numpy deprecation was also addressed in #59 but I think using tiny instead of smallest_normal should be backward compatible.

[fjosw]

Looks like all tests but PYTHON_VERSION=3.6, MINICONDA=C:\Miniconda36-x64, PYTHON_ARCH=64 succeeded. That one exits with

error: Setup script exited with 
Beginning with Matplotlib 3.6, Python 3.8 or above is required.
You are using Python 3.6.5.
This may be due to an out of date pip.
Make sure you have pip >= 9.0.1.

which seems to be unrelated to my changes. I guess this is related to #62 and python 3.6 end of life?

[pbrod]

Thanks @fjosw for the effort of making this pullrequest.

[fjosw]

My pleasure! Could you maybe release a new version on pypi such that dependencies profit from the changes?

[pbrod]

Done!