build(deps): bump setuptools from 75.3.0 to 75.6.0

Bumps [setuptools](https://github.com/pypa/setuptools) from 75.3.0 to 75.6.0.
- [Release notes](https://github.com/pypa/setuptools/releases)
- [Changelog](https://github.com/pypa/setuptools/blob/main/NEWS.rst)
- [Commits](pypa/setuptools@v75.3.0...v75.6.0)

---
updated-dependencies:
- dependency-name: setuptools
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -5,7 +5,7 @@
 # Always use a fixed version, this is important for correct hashing.
 # Dependabot will keep these versions up to date.
 
-setuptools == 75.3.0   # for building Python packages
+setuptools == 75.6.0   # for building Python packages
 pyelftools == 0.31     # for building U-Boot
 unidiff == 0.7.5       # for parsing unified diff
 GitPython == 3.1.43    # for manipulating git repos