Merge pull request #1283 from jakob-keller/ubuntu_focal_20210416

Update Ubuntu 20.04 LTS (Focal Fossa) base image

Author: romainx

base-notebook/Dockerfile

@@ -4,7 +4,7 @@
 # Ubuntu 20.04 (focal)
 # https://hub.docker.com/_/ubuntu/?tab=tags&name=focal
 # OS/ARCH: linux/amd64
-ARG ROOT_CONTAINER=ubuntu:focal-20210401@sha256:5403064f94b617f7975a19ba4d1a1299fd584397f6ee4393d0e16744ed11aab1
+ARG ROOT_CONTAINER=ubuntu:focal-20210416@sha256:86ac87f73641c920fb42cc9612d4fb57b5626b56ea2a19b894d0673fd5b4f2e9
 
 ARG BASE_CONTAINER=$ROOT_CONTAINER
 FROM $BASE_CONTAINER