Update vendored dependencies

This includes github.com/kurin/blazer 0.2.0, which resolves #1291

vendor/google.golang.org/api/pubsub/v1/pubsub-gen.go

@@ -414,7 +414,7 @@ type ModifyPushConfigRequest struct {
 	// An empty `pushConfig` indicates that the Pub/Sub system should
 	// stop pushing messages from the given subscription and allow
 	// messages to be pulled and acknowledged - effectively pausing
-	// the subscription if `Pull` is not called.
+	// the subscription if `Pull` or `StreamingPull` is not called.
 	PushConfig *PushConfig `json:"pushConfig,omitempty"`
 
 	// ForceSendFields is a list of field names (e.g. "PushConfig") to
@@ -874,7 +874,9 @@ type Subscription struct {
 	// call
 	// `ModifyAckDeadline` with the corresponding `ack_id` if
 	// using
-	// pull.
+	// non-streaming pull or send the `ack_id` in
+	// a
+	// `StreamingModifyAckDeadlineRequest` if using streaming pull.
 	// The minimum custom deadline you can specify is 10 seconds.
 	// The maximum custom deadline you can specify is 600 seconds (10
 	// minutes).