Bump matplotlib from 3.3.3 to 3.3.4

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.3.3 to 3.3.4.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](https://github.com/matplotlib/matplotlib/compare/v3.3.3...v3.3.4)

requirements.txt

@@ -7,7 +7,7 @@ kiwisolver==1.3.1
 llvmlite==0.35.0
 importlib-metadata==3.3.0
 joblib==1.0.0
-matplotlib==3.3.3
+matplotlib==3.3.4
 mlxtend==0.18.0
 more-itertools==8.6.0
 numba==0.52.0