prettytable 3.12 introduced ENUMs for
hrules and vrules. Avoid seeing a warning
by adopting this newer code:
check-review-status: commands[0]> tools/check_review_status.py
Delegating release-management tags to MISSING
governance/tools/check_review_status.py:471: DeprecationWarning: the 'ALL' constant is deprecated, use the 'HRuleStyle' and 'VRuleStyle' enums instead
hrules=prettytable.ALL,
Change-Id: I824550165b3e3bb06221ffb0ddaeb90f04fe493c