Bump pytest from 8.2.2 to 8.3.1 in /requirements (AtsushiSakai#1049)

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.2.2 to 8.3.1.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.2.2...8.3.1)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/requirements.txt

@@ -2,7 +2,7 @@ numpy == 2.0.1
 scipy == 1.14.0
 matplotlib == 3.9.1
 cvxpy == 1.5.2
-pytest == 8.2.2 # For unit test
+pytest == 8.3.1 # For unit test
 pytest-xdist == 3.6.1 # For unit test
 mypy == 1.10.1 # For unit test
 ruff == 0.5.2 # For unit test