Pin dependencies and update vendors

vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/marshaler.go

@@ -40,3 +40,9 @@ type EncoderFunc func(v interface{}) error
 
 // Encode delegates invocations to the underlying function itself.
 func (f EncoderFunc) Encode(v interface{}) error { return f(v) }
+
+// Delimited defines the streaming delimiter.
+type Delimited interface {
+	// Delimiter returns the record seperator for the stream.
+	Delimiter() []byte
+}