Bump pytest-xdist from 2.5.0 to 3.0.2 in /requirements (AtsushiSakai#743)

Bumps [pytest-xdist](https://github.com/pytest-dev/pytest-xdist) from 2.5.0 to 3.0.2.
- [Release notes](https://github.com/pytest-dev/pytest-xdist/releases)
- [Changelog](https://github.com/pytest-dev/pytest-xdist/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-xdist@v2.5.0...v3.0.2)

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

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

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

@@ -3,6 +3,6 @@ scipy == 1.9.3
 matplotlib == 3.6.1
 cvxpy == 1.2.1
 pytest == 7.1.3 # For unit test
-pytest-xdist == 2.5.0 # For unit test
+pytest-xdist == 3.0.2 # For unit test
 mypy == 0.982 # For unit test
 flake8 == 5.0.4 # For unit test