Set up auto update version for pip or conda-forge/bioconda on release

[m-d-grunnill]

For pip: (@terrycojones I may need you to email me the pip api token for beast2-xml for these options.)

• https://github.com/marketplace/actions/pypi-publish
• https://github.com/acorg/beast2-xml/new/master?filename=.github%2Fworkflows%2Fpython-publish.yml&workflow_template=ci%2Fpython-publish
• https://docs.github.com/en/actions/use-cases-and-examples/building-and-testing/building-and-testing-python#publishing-to-package-registries

For conda-forge/bioconda:

• https://github.com/marketplace/actions/build-and-publish-conda-packages-to-anaconda-org

[m-d-grunnill]

Done for pip see python-publish.yml.