Fix typo in math_verify package name

[theodorosploumis]

The real package path is https://pypi.org/project/math-verify.
When I run pipx install optillm it does not install the math-verify package so the command optillm fails like this:

Traceback (most recent call last):
  File "/home/XXX/.local/bin/optillm", line 3, in <module>
    from optillm import main
  File "/home/XXX/.local/share/pipx/venvs/optillm/lib/python3.12/site-packages/optillm/__init__.py", line 5, in <module>
    from .server import (
  File "/home/XXX/.local/share/pipx/venvs/optillm/lib/python3.12/site-packages/optillm/server.py", line 34, in <module>
    from optillm.cepo.cepo import cepo, CepoConfig, init_cepo_config
  File "/home/XXX/.local/share/pipx/venvs/optillm/lib/python3.12/site-packages/optillm/cepo/cepo.py", line 6, in <module>
    import math_verify

ModuleNotFoundError: No module named 'math_verify'

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