PyWinpty release v2.0.4

Minor pywinpty release that brings support for both winpty-rs v0.3.4 and windows-2022 CI images. Python 3.6 support was dropped officially.

What's Changed

• PR: Update winpty-rs to v0.3.4 by @andfoy in #219

Full Changelog: v2.0.3...v2.0.4