feat: Add pixi environment (#534)

* feat: Add pixi environment

* Add pixi manifest pixi.toml for Linux x86, macOS arm64, Windows 64.

* ci: Update CI workflow and unify to one

* Enable workflow dispatch.
* Add concurrency limits.
* Use pixi for CI workflow.
* Unify to a single workflow for all OS tested

* feat: Add pixi lock file

* Ensure tensorflow-cpu installed on Windows

* fix package check

* fix package check

* simplification plus uv and pip runners

* some fixes to pixi and pip

* create pixi.lock

* fix pixi.lock issue

* another attempt trying to fix get_packages

* another attempt trying to fix get_packages

* clean up python_environment_check.py

* updated runner and docs

* use bash

* proper env activiation

* proper env activiation

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Co-authored-by: rasbt <mail@sebastianraschka.com>