Add Ubuntu 20.04 support and use Python 3 (#6157)

roles/bootstrap-os/tasks/bootstrap-debian.yml

@@ -2,7 +2,7 @@
 # Some Debian based distros ship without Python installed
 
 - name: Check if bootstrap is needed
-  raw: which python
+  raw: which python3
   register: need_bootstrap
   failed_when: false
   changed_when: false
@@ -77,10 +77,10 @@
     - '"bionic" in os_release.stdout'
     - need_dnssec_allow_downgrade.rc
 
-- name: Install python
+- name: Install python3
   raw:
     apt-get update && \
-    DEBIAN_FRONTEND=noninteractive apt-get install -y python-minimal
+    DEBIAN_FRONTEND=noninteractive apt-get install -y python3-minimal
   become: true
   environment: {}
   when:
@@ -91,4 +91,5 @@
   package:
     name: dbus
     state: present
+    use: apt
   become: true