Update flake8-builtins requirement in /src/bindings/python

Updates the requirements on [flake8-builtins](https://github.com/gforcada/flake8-builtins) to permit the latest version.
- [Changelog](https://github.com/gforcada/flake8-builtins/blob/main/CHANGES.rst)
- [Commits](gforcada/flake8-builtins@0.1...2.5.0)

---
updated-dependencies:
- dependency-name: flake8-builtins
  dependency-type: direct:production
...

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

src/bindings/python/requirements_test.txt

@@ -21,7 +21,7 @@ flake8-rst-docstrings
 pygments
 flake8-string-format
 flake8-variables-names
-flake8_builtins<2.3.0
+flake8_builtins<2.6.0
 flake8_coding
 flake8_commas
 flake8_pep3101