Let's bring in the latest release of Containerd, 1.6.1, released on
March 2nd, 2022.
With this, we take the opportunity to remove containerd/api reference as
we shouldn't need a separate module only for the API.
Here's the list of changes needed in the code due to the bump:
* stop using `grpc.WithInsecure()` as it's been deprecated
- use `grpc.WithTransportCredentials(insecure.NewCredentials())`
instead
Fixes: #3820
Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>
