fix run_command() to handle passed versions correctly

[KiriakosGeorgiou]

check_txn_idle() introduced multiple '>' version ckecks to handle v10 postgres, but run_command() does not correctly implement such multiple '>' or '<' version checks.

run_command() should match the highest '<' or '>' version.

The modified implementation works if and only if the versions are passed in ascending order, which is the way check_txn_idle() currently passes them.