Add a bump version workflow to automate release tagging

[matthewfeickert]

@dguest now that PR #62 is in there should be a patch release so that info gets propagated out to PyPI. How do you feel about even more automation to make cutting release tags only require 1 button click and a tag entry? 🙂 c.f. recast-hep/recast-atlas#68

[matthewfeickert]

@dguest now that PR #62 is in there should be a patch release so that info gets propagated out to PyPI.

Also pandamonium is installable (and probably works) in Python 3.10. 👍 So that should get added to

pandamonium/setup.cfg

Lines 17 to 28 in b8471cc

	classifiers =
	Development Status :: 4 - Beta
	License :: OSI Approved :: BSD License
	Intended Audience :: Science/Research
	Topic :: Scientific/Engineering
	Topic :: Scientific/Engineering :: Physics
	Programming Language :: Python :: 2.7
	Programming Language :: Python :: 3
	Programming Language :: Python :: 3.6
	Programming Language :: Python :: 3.7
	Programming Language :: Python :: 3.8
	Programming Language :: Python :: 3.9