Let list[] and dict[] being valid in python 3.8

We are mostly all developing using recent versions supporting this, so
such syntax is bound to evade our reviews anyway.  Since there is a
__future__ flag valid since 3.7, let's use it instead.

Signed-off-by: Yann Dirson <[email protected]>

Author: ydirson

lib/host.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import logging
 import os
 import shlex

lib/vm.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import logging
 import os
 import subprocess