Update mypy to 0.981
Update mypy to 0.981

Depends-On: I6ec5a3e7a3626d1fcfdc9f2034c765e617e2057f
Change-Id: I8d6ca5a032806ddd3ebb8cd65b42642c06b3be3c

openstack/cinder,mahak/cinder,mahak/cinder,openstack/cinder