Update Dask version to 2021.8.1 (#178)

Co-authored-by: James Bourbeau <[email protected]>

Author: github-actions[bot]

build/docker-compose.yml

@@ -6,7 +6,7 @@ services:
       context: ../base
       dockerfile: Dockerfile
       args:
-        release: "2021.8.0"
+        release: "2021.8.1"
     image: daskdev/dask:latest
     hostname: dask-scheduler
     ports: