Update matplotlib requirement from ~=3.3.2 to ~=3.3.3 (#675)

Updates the requirements on [matplotlib](https://github.com/matplotlib/matplotlib) to permit the latest version.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.3.2...v3.3.3)

Signed-off-by: dependabot[bot] <support@github.com>

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

dev-requirements.txt

@@ -5,7 +5,7 @@ pytest ~=6.1.2
 vcrpy ~=4.1.1
 doctr ~=1.8.0
 ipython ~=7.19.0
-matplotlib ~=3.3.2
+matplotlib ~=3.3.3
 numpydoc ~=1.1.0
 requests-mock ~=1.8.0
 sphinx ~=3.3.1