Release 0.3.0

[shachafl]

Following the "Deployment" steps in the Makefile, I have done the following:

1. Updated the CHANGELOG.md file
2. Made some minor corrections to resolve errors when running example pipelines
3. Corrected the "Windows" Operating System classifier in setup.cfg

I have also uploaded the package to TestPyPI, but couldn't pip install ... as some dependencies don't work via testpypi.

[shachafl]

@berl, @njmei, can one of you please review this PR?

[njmei]

@shachafl I see a lot of fix entries in the "changelog" file but I don't see the corresponding commits in this PR? Were they already merged into the master branch?

[shachafl]

@shachafl I see a lot of fix entries in the "changelog" file but I don't see the corresponding commits in this PR? Were they already merged into the master branch?

@njmei, you are right, most commits up to this PR were already merged to master. Also, last release (and tag) was about 3 years ago and so, when generating the CHANGLOG.md via make release-changelog it added all PRs since the last tag. I ended up removing some redundancy, but kept most of it for historical reference.
Let me know if you think some entries should be removed.