pypi: pin setuptools<77 to dodge PEP 639 license validation crash

Real root cause of the macOS/Windows wheel failures (Linux x86_64 escaped
via different Python images): setuptools 77.0+ canonicalizes the license
expression in pyproject.toml via packaging.licenses, which requires
packaging>=24.2 IN THE BUILD ENVIRONMENT. cibuildwheel's isolated build
envs (especially cp39) don't pull that in by default, so they hit:

  ImportError: Cannot import `packaging.licenses`.
  Setuptools>=77.0.0 requires "packaging>=24.2" to work properly.

Two-part fix:
  - Pin setuptools<77 in build-system.requires
  - Also list packaging>=24.2 explicitly so future setuptools upgrades
    don't reintroduce the issue

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: unamedkr

bindings/python/pyproject.toml

@@ -1,5 +1,8 @@
 [build-system]
-requires = ["setuptools>=64", "wheel"]
+# setuptools 77+ enforces PEP 639 license validation which requires
+# packaging>=24.2 in the build env — older Python builds in cibuildwheel
+# don't have it. Pin <77 until we migrate fully to PEP 639.
+requires = ["setuptools>=64,<77", "wheel", "packaging>=24.2"]
 build-backend = "setuptools.build_meta"
 
 [project]