Fix z3 version checks
Fix z3 version checks

We were comparing 4.11.2 with 4.3.2 by comparing
["4", "11", "2"] >= ["4", "3", "2"]

Which would return False because "11" >= "3" is false.

This patch changes this to read the version components as
integers instead of strings.

ucsd-progsys/liquid-fixpoint