cmake: drop "mypy" from tox envlist of "qa"
this change partially reverts
81305b0da9a3e04633c022b12644e2975aa46a0d,
otherwise we have following errors:
tasks/vstart_runner.py:691: error: Definition of "_run_python" in base class "LocalCephFSMount" is incompatible with definition in base class "CephFSMount"
tasks/vstart_runner.py:705: error: Definition of "_run_python" in base class "LocalCephFSMount" is incompatible with definition in base class "CephFSMount"
Signed-off-by: Kefu Chai <kchai@redhat.com>