Update cython requirement from <4,>=3.2.5 to >=3.2.6,<4 in /sdks/python (#39099)

Updates the requirements on [cython](https://github.com/cython/cython) to permit the latest version.
- [Release notes](https://github.com/cython/cython/releases)
- [Changelog](https://github.com/cython/cython/blob/master/CHANGES.rst)
- [Commits](cython/cython@3.2.5...3.2.6)

---
updated-dependencies:
- dependency-name: cython
  dependency-version: 3.2.6
  dependency-type: direct:development
...

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Author: dependabot[bot]

sdks/python/pyproject.toml

@@ -32,7 +32,7 @@ requires = [
     # Numpy headers
     "numpy>=1.14.3,<2.5.0", # Update setup.py as well.
     # having cython here will create wheels that are platform dependent.
-    "cython>=3.2.5,<4",
+    "cython>=3.2.6,<4",
     ## deps for generating external transform wrappers:
     # also update PyYaml bounds in sdks:python:generateExternalTransformsConfig
     'pyyaml>=3.12,<7.0.0',