chore: drop setuptools<81 pin — dead after #716 (#718)

The pin's comment attributes it to "sf_tools/python-pysap importing
pkg_resources", but direct testing in the shapepipe container shows:

- `sf_tools` 2.0.4 imports cleanly on setuptools 82 (no pkg_resources
  reference in its source).
- `python-pysap` master has no `pkg_resources` usage in either its
  package `__init__.py` or `setup.py`.
- The only runtime dependency in the shapepipe stack that actually used
  `pkg_resources` (via `pkg_resources.get_distribution("sip_tpv")`) was
  `sip_tpv`, which was removed from shapepipe entirely in #716.

So the historical need for the pin was sip_tpv, mis-attributed at
commit time. Post-#716 there's no remaining shapepipe dep that needs
pkg_resources, so the pin is dead.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: cailmdaley

pyproject.toml

@@ -30,7 +30,6 @@ dependencies = [
     "PyQt5",
     "pyqtgraph",
     "reproject",
-    "setuptools<81", # workaround for sf_tools/python-pysap importing pkg_resources
     "sf_tools",
     "skaha",
     "sqlitedict",