Move badge from Travis-CI to GH actions

[jrief]

• move badge still pointing onto dysfunctional Travis-CI to GitHub actions.
• prepare a GH action to automatically publish new releases upon tagging.

[jrief]

@selwin The CI-badge on the README file still pointed onto the dysfunctional Travis-CI runner.

[selwin]

@jrief I'm a little bit nervous about the Github action to automatically publish to PyPI, but would like to give it a try.

Reading the YAML file, I'd first need to setup secrets.PYPI_API_TOKEN_POST_OFFICE, correct?

[jrief]

Reading the YAML file, I'd first need to setup secrets.PYPI_API_TOKEN_POST_OFFICE, correct?

correct.

I'm a little bit nervous about the Github action to automatically publish to PyPI, but would like to give it a try.

I can change that, so that new versions have to be manually triggered. In my projects, I always use the tagging event for this purpose.

[selwin]

I can change that, so that new versions have to be manually triggered. In my projects, I always use the tagging event for this purpose.

Yes please :)