Plan for next release - 1.0.0?

[consideRatio]

@manics suggested we get windows support for jupyter-server-proxy's next release, which requires this project to get #26 merged and then a new release made.

I suggest we go for 1.0.0 after getting a few things done, where I propose 1.0.0 over 0.5.0 in order to arrive to 1.0.0 where choosing future versions is far easier based on the semver2 meaning of major.minor.patch version identifiers.

PRs in need of review

• Add support for Windows platform #26
• pre-commit: add autoflake hook, use dedicated .flake8 config, detail tweaks to RELEASE.md #29
• Drop support for Python 3.7 #30
• docs: fix github test passing badge #31

Issues to resolve

• Add missing git tags for 0.1 and 0.3 releases, and backfill changelog for 0.1, 0.2, 0.3, 0.4 #35