CONTRIBUTING.md: incorrect pipx documentation link

[star-lord1234]

Issue

In CONTRIBUTING.md, the link for pipx currently points to the Poetry website instead of the official pipx documentation.

Current link:

[pipx](https://python-poetry.org/)

Expected

The link should point to the official pipx documentation:

[pipx](https://pipx.pypa.io/)

Impact

This may confuse contributors who are trying to install pipx, as they are directed to the Poetry website rather than the pipx documentation.

Suggested fix

Update the link in CONTRIBUTING.md to use the official pipx documentation URL.

[khushthecoder]

Hi @jonbrenas , I’ve created a PR for this issue and all the test cases are passing. Could you please review it? Let me know if any further changes are needed — I’m available to work on them.#1145