PyWinpty release v2.0.0

Major pywinpty release that simplifies the dependencies as well the building environment. The PTY implementation details were moved into their own library in rust, winpty-rs and C++ dependencies were dropped, which implies that this library functions as a simple PyO3 wrapper that calls winpty-rs without any added complexities.

Backward compatible changes

• PTY and PtyProcess no longer accept an encoding keyword argument.

Performance improvements

• PtyProcess reading thread is now blocking, and no longer consumes CPU unnecessarily.

Other improvements

• The backend argument is now working on PtyProcess.

What's Changed

• Update windows requirement from 0.26.0 to 0.28.0 by @dependabot in #203
• Update windows requirement from 0.28.0 to 0.29.0 by @dependabot in #204
• PR: Move implementation to use winpty-rs by @andfoy in #206

Full Changelog: v1.1.6...v2.0.0