Rename project "pyomo" in setup.py [PEP 625]

[jsiirola]

Fixes # .

Summary/Motivation:

PyPI is rejecting Pyomo wheels because the project name was capitalized. This resolves that error.

Changes proposed in this PR:

• rename "Pyomo" -> "pyomo"

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[blnicho]

I kicked off the wheel builder GHA workflow on this branch: https://github.com/blnicho/pyomo/actions/runs/11903047078

I'm not really sure how to check if these wheels satisfy PEP 625 or if we still need this PR since PyPI reverted the strict enforcement of the PEP.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.71%. Comparing base (038f38b) to head (be24275).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3430      +/-   ##
==========================================
+ Coverage   88.66%   88.71%   +0.04%     
==========================================
  Files         882      882              
  Lines      100623   100623              
==========================================
+ Hits        89216    89265      +49     
+ Misses      11407    11358      -49     

Flag	Coverage Δ
linux	86.17% <ø> (+<0.01%)	⬆️
osx	76.19% <ø> (ø)
other	86.66% <ø> (+<0.01%)	⬆️
win	84.55% <ø> (+<0.01%)	⬆️

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