Bump matplotlib from 3.5.1 to 3.5.2 in /requirements (#678)

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.5.1 to 3.5.2.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](https://github.com/matplotlib/matplotlib/compare/v3.5.1...v3.5.2)

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

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

requirements/requirements.txt

@@ -1,7 +1,7 @@
 numpy == 1.22.3
 scipy == 1.8.0
 pandas == 1.4.2
-matplotlib == 3.5.1
+matplotlib == 3.5.2
 cvxpy == 1.2.0
 pytest == 7.1.2 # For unit test
 pytest-xdist == 2.5.0 # For unit test