Bump matplotlib from 3.7.0 to 3.7.1 in /requirements (AtsushiSakai#800)

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.7.0 to 3.7.1.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.7.0...v3.7.1)

---
updated-dependencies:
- dependency-name: matplotlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

@@ -1,6 +1,6 @@
 numpy == 1.24.2
 scipy == 1.10.1
-matplotlib == 3.7.0
+matplotlib == 3.7.1
 cvxpy == 1.3.0
 pytest == 7.2.1 # For unit test
 pytest-xdist == 3.2.0 # For unit test