tools: make use of modern syntax in tools/install.py

[avivkeller]

From my perspective, this file relies on a few outdated practices:

• Not using pathlib
• Not using f-strings

If there is a reason for these outdated practices, feel free to let me know :-)

[richardlau]

This removes AIX and z/OS code.

[aduh95]

If there is a reason for this, feel free to let me know :-)

Shouldn't it be the other way around? If there's a reason not to do this, you should be the one letting us know given you're the one suggesting the change. It's a very large change hard to review, and it's unclear what we get out of it.

[avivkeller]

I've simplified. To clarify, my goal was to make this use pathlib, f-strings, a similar.