Release 1.3.3

This is mostly a maintenance release, however I've also started trying to whittle down the number of warnings I'm getting from the various linters I run as part of tests.

• new: adding support for newer python releases (3.8, 3.9, 3.10)
• fix: various typos in docstrings (#39, )
• fix: change use of deprecated upload-dir to upload_dir in setup.cfg (#34)
• fix: Runtime class now sets None for stdout by default (#24)
• fix: corrected argument order in several calls to super() (#18)
• cleanup: many bits of code tidying to eliminate linter warnings

Thanks to @shepherdjay, @sbraz, and @Josef-Friedrich for your contributions to this release.

Please note the Discussion about a potential new policy about Python release support in future versions of nagiosplugin. I'd like to invite anyone using the library to please read and comment on that discussion.

Cheers!