[clang-tools-extra] Move Piotr Zegar to the inactive maintainers list (PR #176967)

[Julian Schmidt via cfe-commits]

5chmidti wrote:

I was very inactive last year, though a good majority of that was outside my control. I'm ramping up my activity back up, so I want to stay on as a maintainer. We do need the review bandwidth ^^

> I've not heard back yet from @5chmidti.

It went to spam :)

https://github.com/llvm/llvm-project/pull/176967