fixup_stuff prettytable min version

The minimum prettytable version is changed from 0.6 to 0.7
 in the global requirements.

If the system has an older prettytable version the fixup_stuff does not
takes effect in time, because at fixup time the system has the old
version.

Ensure the fixup installs the minimum required version in time.

Change-Id: If1737dacb25db73b68e707953d05576ad8a97da7
Merge "fixup_stuff prettytable min version"