Bump matplotlib from 3.4.3 to 3.5.0 (AtsushiSakai#575)

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.4.3 to 3.5.0.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.4.3...v3.5.0)

---
updated-dependencies:
- dependency-name: matplotlib
  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.txt

@@ -1,7 +1,7 @@
 numpy == 1.21.4
 scipy == 1.7.2
 pandas == 1.3.4
-matplotlib == 3.4.3
+matplotlib == 3.5.0
 cvxpy == 1.1.17
 pytest == 6.2.5 # For unit test
 pytest-xdist == 2.4.0 # For unit test