1. Docker v20 is the default version for git action, dns should be set manually.
Python v3.8 is the default version for git action, so remove deployment for python v3.6.
2. Some of API tests would be affect by docker v20, like manifest get
message will not be triggered if there is one locally, to avoid this
impact, API tests will be tested with docker E2E image, in this image,
docker v19 is enabled.
Signed-off-by: danfengliu <danfengl@vmware.com>
