Remove pytest from production requirements

[joanise]

Bug description

I'm accidentally made pytest a prod requirements in either #792 or #794, this needs to be undone.

We could either:

• fix everyvoice/cli.py so it does not indirectly import pytest, while still preserving the hidden everyvoice test command
• or, since I don't believe anyone ever uses everyvoice test, and just running pytest is actually shorter, I think we should remove everyvoice test from the CLI instead.

How to reproduce the bug

Checkout origin/main and run everyvoice -h when pytest is not installed:

• either do a fresh venv and only install uv pip install -e .
• or from an existing venv run uv pip uninstall pytest

Error messages and logs

$ everyvoice -h
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Users\joanise\sandboxes\EveryVoice\.venv\Scripts\everyvoice.exe\__main__.py", line 4, in <module>
  File "C:\Users\joanise\sandboxes\EveryVoice\everyvoice\cli.py", line 67, in <module>
    from everyvoice.run_tests import SUITE_NAMES, run_tests
  File "C:\Users\joanise\sandboxes\EveryVoice\everyvoice\run_tests.py", line 12, in <module>
    import pytest
ModuleNotFoundError: No module named 'pytest'

Environment

No response

More info

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