build(deps): bump pytest from 8.4.2 to 9.0.0 in /requirements

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.4.2 to 9.0.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.4.2...9.0.0)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

requirements/requirements.txt

@@ -3,7 +3,7 @@ scipy == 1.16.3
 matplotlib == 3.10.7
 cvxpy == 1.7.3
 ecos == 2.0.14
-pytest == 8.4.2 # For unit test
+pytest == 9.0.0 # For unit test
 pytest-xdist == 3.8.0 # For unit test
 mypy == 1.18.2 # For unit test
 ruff == 0.14.3 # For unit test