fix(dev): cap numpy<2.5 in dev extra to unblock mypy typecheck

[davidnichols-ops]

Summary

• numpy 2.5.0 (released 2026-06-21) ships type stubs using PEP 695 type statement syntax, which mypy cannot parse under python_version = "3.10" (set in pyproject.toml).
• With no upper bound on numpy in the dev extra, pip install ".[dev]" now resolves numpy 2.5.0, and the mypy roboflow step in make check_code_quality (run in CI via .github/workflows/test.yml) fails across the entire 3.10–3.13 matrix.
• This is a numpy × mypy version interaction, not a bug in roboflow code. See CI typecheck fails: numpy 2.5.0 stubs use PEP 695 type statements, incompatible with mypy python_version = "3.10" #498 for the full diagnosis.
• Fix: cap numpy<2.5 in the dev extra in setup.py only. pip intersects this with the runtime requirement (numpy>=1.18.5 in requirements.txt), so dev/typecheck installs get >=1.18.5,<2.5 while end-user runtime installs stay unconstrained.
• setup_slim.py is untouched — the slim distribution has no numpy dependency and its CI job does not run mypy.

Before (unpatched, numpy 2.5.0)

$ pip install -e ".[dev]"          # resolves numpy 2.5.0
$ mypy roboflow
numpy/__init__.pyi:737: error: Type statement is only supported in Python 3.12 and greater  [syntax]
Found 1 error in 1 file (errors prevented further checking)
exit: 2

After (patched, numpy 2.4.6)

$ pip install -e ".[dev]"          # cap forces numpy 2.4.6
$ make check_code_quality
ruff format roboflow --check    -> 69 files already formatted
ruff check roboflow             -> All checks passed!
mypy roboflow                   -> Success: no issues found in 69 source files

$ python -m unittest
Ran 729 tests in 17.845s
OK (skipped=1)

The cap is enforced by pip's resolver: pip install -e ".[dev]" "numpy>=2.5" against the patched setup.py correctly fails with ResolutionImpossible.

Test plan

• ruff format roboflow --check passes (69 files)
• ruff check roboflow passes (All checks passed!)
• mypy roboflow passes (Success: no issues found in 69 source files)
• python -m unittest passes (729 tests, OK skipped=1)
• pip resolver enforces the cap (numpy>=2.5 + patched dev extra -> ResolutionImpossible)
• Runtime requirements.txt unchanged — end-user installs unaffected

Fixes #498