Drop pytz requirement, appears to be unused

[opoplawski]

Description

pytz appears to be unused in the code, drop the requirement.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[codspeed-hq]

Merging this PR will not alter performance

✅ 5 untouched benchmarks

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_{Comparing opoplawski:drop-pytz (def1826) with main (da72aa8)}