Bump cython from 3.1.3 to 3.1.6 in /source/cython_example

Bumps [cython](https://github.com/cython/cython) from 3.1.3 to 3.1.6.
- [Release notes](https://github.com/cython/cython/releases)
- [Changelog](https://github.com/cython/cython/blob/master/CHANGES.rst)
- [Commits](cython/cython@3.1.3...3.1.6)

---
updated-dependencies:
- dependency-name: cython
  dependency-version: 3.1.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

source/cython_example/requirements.txt

@@ -1 +1 @@
-Cython==3.1.3
+Cython==3.1.6