Bump types-python-dateutil from 2.8.4 to 2.8.6

Bumps [types-python-dateutil](https://github.com/python/typeshed) from 2.8.4 to 2.8.6.
- [Release notes](https://github.com/python/typeshed/releases)
- [Commits](https://github.com/python/typeshed/commits)

---
updated-dependencies:
- dependency-name: types-python-dateutil
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

requirements-dev.txt

@@ -17,7 +17,7 @@ isort==5.10.1
 time-machine==2.5.0
 
 # Convert jupyter notebooks to markdown documents
-nbconvert==6.3.0
+nbconvert==6.4.0
 
 # mypy types
 types-cachetools==4.2.7
@@ -26,4 +26,4 @@ types-requests==2.26.3
 types-tabulate==0.8.4
 
 # Extensions to datetime library
-types-python-dateutil==2.8.4
+types-python-dateutil==2.8.6