build(deps): update matplotlib requirement from ~=3.5.3 to ~=3.6.0 (#318)

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@v3.5.3...v3.6.0)

---
updated-dependencies:
- dependency-name: matplotlib
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

requirements-docs.txt

@@ -7,7 +7,7 @@ nbsphinx~=0.8
 jinja2<4.0
 geopandas~=0.11.1
 hvplot~=0.8.1
-matplotlib~=3.5.3
+matplotlib~=3.6.0
 geojson~=2.5.0
 pygeoif~=0.7
 pydata-sphinx-theme~=0.10