vendor: Bump to grpc v1.12.2

vendor/google.golang.org/grpc/grpclog/logger.go

@@ -19,6 +19,7 @@
 package grpclog
 
 // Logger mimics golang's standard Logger as an interface.
+//
 // Deprecated: use LoggerV2.
 type Logger interface {
 	Fatal(args ...interface{})
@@ -31,6 +32,7 @@ type Logger interface {
 
 // SetLogger sets the logger that is used in grpc. Call only from
 // init() functions.
+//
 // Deprecated: use SetLoggerV2.
 func SetLogger(l Logger) {
 	logger = &loggerWrapper{Logger: l}