ci: Reinstate Ubuntu Focal support

Reinstate support for Ubuntu Focal, which was previously removed in
commit 229ebbd.

Refs #206

.circleci/config.yml

@@ -159,6 +159,18 @@ jobs:
  - run: *copy-image
  - run: *build-deb
 
+ build-ubuntu-focal:
+ docker:
+ - image: ubuntu:20.04
+ resource_class: medium+
+ steps:
+ - checkout
+ - run: *provide-podman
+ - run: *install-dependencies-deb
+ - restore_cache: *restore-cache
+ - run: *copy-image
+ - run: *build-deb
+
  build-debian-bookworm:
  docker:
  - image: debian:bookworm
@@ -301,6 +313,12 @@ jobs:
  PACKAGE_TYPE: "deb"
  PACKAGECLOUD_DISTRO: "ubuntu/jammy"
  <<: *deploy-packagecloud
+ - run:
+ name: Deploy ubuntu/focal
+ environment:
+ PACKAGE_TYPE: "deb"
+ PACKAGECLOUD_DISTRO: "ubuntu/focal"
+ <<: *deploy-packagecloud
 
 workflows:
  version: 2
@@ -315,6 +333,9 @@ workflows:
  - build-ubuntu-jammy:
  requires:
  - build-container-image
+ - build-ubuntu-focal:
+ requires:
+ - build-container-image
  - build-debian-bullseye:
  requires:
  - build-container-image