Bump dask from 0.20.0 to 2021.10.0

Bumps [dask](https://github.com/dask/dask) from 0.20.0 to 2021.10.0.
- [Release notes](https://github.com/dask/dask/releases)
- [Changelog](https://github.com/dask/dask/blob/main/docs/release-procedure.md)
- [Commits](https://github.com/dask/dask/compare/0.20.0...2021.10.0)

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

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

requirements.txt

@@ -4,7 +4,7 @@ certifi==2018.10.15
 chardet==3.0.4
 cloudpickle==0.6.1
 cycler==0.10.0
-dask==0.20.0
+dask==2021.10.0
 decorator==4.3.0
 Django==2.0.7
 django-rest-framework==0.1.0