Migrate to containerd v1.7.0 and update dependencies

* Updates containerd to v1.7.0 and new binary for 32-bit
Arm OSes.
* Updates Go dependencies - openfaas and external

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/google.golang.org/grpc/internal/grpcutil/method.go

@@ -25,7 +25,6 @@ import (
 
 // ParseMethod splits service and method from the input. It expects format
 // "/service/method".
-//
 func ParseMethod(methodName string) (service, method string, _ error) {
 	if !strings.HasPrefix(methodName, "/") {
 		return "", "", errors.New("invalid method name: should start with /")
@@ -39,6 +38,11 @@ func ParseMethod(methodName string) (service, method string, _ error) {
 	return methodName[:pos], methodName[pos+1:], nil
 }
 
+// baseContentType is the base content-type for gRPC.  This is a valid
+// content-type on it's own, but can also include a content-subtype such as
+// "proto" as a suffix after "+" or ";".  See
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests
+// for more details.
 const baseContentType = "application/grpc"
 
 // ContentSubtype returns the content-subtype for the given content-type.  The