chore: drop support for Ubuntu 20.04 Focal

Focal was EOL on May 31, 2025.

Author: josegonzalez

Makefile

@@ -130,7 +130,6 @@ release-packagecloud:
 	@$(MAKE) release-packagecloud-deb
 
 release-packagecloud-deb: build/deb/$(NAME)_$(VERSION)_all.deb
-	package_cloud push $(PACKAGECLOUD_REPOSITORY)/ubuntu/focal build/deb/$(NAME)_$(VERSION)_all.deb
 	package_cloud push $(PACKAGECLOUD_REPOSITORY)/ubuntu/jammy build/deb/$(NAME)_$(VERSION)_all.deb
 	package_cloud push $(PACKAGECLOUD_REPOSITORY)/ubuntu/noble build/deb/$(NAME)_$(VERSION)_all.deb
 	package_cloud push $(PACKAGECLOUD_REPOSITORY)/debian/bullseye build/deb/$(NAME)_$(VERSION)_all.deb