Fixes #5454 make build-debs-focal

This adds a new build target to build the Debian packages on Focal.
It also includes two variables to be used as ansible override
during future build steps in Ansible.

Makefile

@@ -329,6 +329,13 @@ build-debs-notest: ## Build SecureDrop Debian packages without running tests.
 	@$(SDROOT)/devops/scripts/build-debs.sh notest
 	@echo
 
+.PHONY: build-debs-focal
+build-debs-focal: ## Build and test SecureDrop Debian packages.
+	@echo "Building SecureDrop Debian packages..."
+	@$(SDROOT)/devops/scripts/build-debs.sh notest focal
+	@echo
+
+
 
 ########################
 #

molecule/builder-focal/ansible-override-vars.yml

@@ -0,0 +1,3 @@
+---
+securedrop_build_focal_support: True
+securedrop_staging_install_target_distro: "focal"

molecule/builder-focal/molecule.yml

@@ -39,6 +39,8 @@ provisioner:
   inventory:
     links:
       group_vars: ../../install_files/ansible-base/group_vars
+  options:
+    e: "@ansible-override-vars.yml"
   config_options:
     defaults:
       interpreter_python: auto