Update ubuntu:focal Docker digest to bb1c416 (#3336)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

docker/sql/Dockerfile

@@ -6,7 +6,7 @@
 
 # Ubuntu 20.04 LTS ("Focal Fossa")
 # MS SQL Sever does not yet support later versions
-FROM ubuntu:focal@sha256:f2034e7195f61334e6caff6ecf2e965f92d11e888309065da85ff50c617732b8
+FROM ubuntu:focal@sha256:bb1c41682308d7040f74d103022816d41c50d7b0c89e9d706a74b4e548636e54
 
 # Install SQL Server 2019 and after its prerequisites
 RUN export DEBIAN_FRONTEND=noninteractive && \