Cleanup fermi.py and astroeqs.py

[xshaokun]

Currently, fermi.py and astroeqs.py are ignored by pre-commit hooks to avoiding raising errors by ruff. They should be considered to be archived or be cleaned up to fix the part that raising errors.

ruff.....................................................................Failed
- hook id: ruff
- exit code: 1

pytools/astroeqs.py:133:26: F821 Undefined name `P`
pytools/astroeqs.py:133:30: F821 Undefined name `T`
pytools/fermi.py:629:14: F821 Undefined name `data`
pytools/fermi.py:637:42: F821 Undefined name `times`
pytools/fermi.py:637:48: F821 Undefined name `kprint`
pytools/fermi.py:647:23: F821 Undefined name `ylabel`
pytools/fermi.py:648:35: F821 Undefined name `ylabel`
pytools/fermi.py:653:20: F821 Undefined name `data`
pytools/fermi.py:656:34: F821 Undefined name `var`
pytools/fermi.py:656:39: F821 Undefined name `kprint`
pytools/fermi.py:790:30: F821 Undefined name `R`
pytools/fermi.py:795:34: F821 Undefined name `R`
pytools/fermi.py:795:37: F821 Undefined name `z`
pytools/fermi.py:797:34: F821 Undefined name `R`
pytools/fermi.py:797:37: F821 Undefined name `z`
pytools/fermi.py:800:49: F821 Undefined name `times`
pytools/fermi.py:800:59: F821 Undefined name `kprint`
pytools/fermi.py:814:23: F821 Undefined name `clabel`
pytools/fermi.py:816:45: F821 Undefined name `clabel`
pytools/fermi.py:818:59: F821 Undefined name `clabel`
pytools/fermi.py:821:20: F821 Undefined name `data`
pytools/fermi.py:824:35: F821 Undefined name `var`
pytools/fermi.py:824:40: F821 Undefined name `kprint`