Pin to Setuptools<81

[vatsal-j]

Last week Setuptools 82.0.0 was released that removed pkg_resources, which breaks things for AIT Core:

>>> from ait.core import tlm
2026-02-17T17:12:55.559 | WARNING  | Config parameter command.history.filename specifies nonexistent path /proj/emit/ops/data/MT-400057/cmdhist.pcap
...
2026-02-17T17:12:55.574 | WARNING  | Config parameter planning.gypsum.filename specifies nonexistent path /proj/emit/ops/planning/MT-400057/clasp/gypsum/gypsum.tif
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jhalani/anaconda3/envs/emit-ios/lib/python3.10/site-packages/ait/core/tlm.py", line 25, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

We switched to importlib on our project when we saw the deprecation warnings, but a new install will break because of AIT Core. Pinning to Setuptools<81 fixes this:

>>> from ait.core import tlm
2026-02-17T17:14:41.300 | WARNING  | Config parameter command.history.filename specifies nonexistent path /proj/emit/ops/data/MT-400057/cmdhist.pcap
...
2026-02-17T17:14:41.312 | WARNING  | Config parameter planning.gypsum.filename specifies nonexistent path /proj/emit/ops/planning/MT-400057/clasp/gypsum/gypsum.tif
/Users/jhalani/anaconda3/envs/emit-ios/lib/python3.10/site-packages/ait/core/tlm.py:25: UserWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html. The pkg_resources package is slated for removal as early as 2025-11-30. Refrain from using this package or pin to Setuptools<81.
  import pkg_resources
2026-02-17T17:14:41.493 | INFO     | Attempting to load leapseconds.dat
2026-02-17T17:14:41.494 | INFO     | Loaded leapseconds config file successfully
2026-02-17T17:14:41.495 | INFO     | Leapseconds data valid until 06/28/2026