lnrpc: update docker base image version

lnrpc/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.19.2-buster
+FROM golang:1.20.4-buster
 
 RUN apt-get update && apt-get install -y \
   git \

lnrpc/gen_protos_docker.sh

@@ -6,7 +6,7 @@ set -e
 DIR="$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
 
 # golang docker image version used in this script.
-GO_IMAGE=golang:1.19.7-alpine
+GO_IMAGE=golang:1.20.4-alpine
 
 PROTOBUF_VERSION=$(docker run --rm -v $DIR/../:/lnd -w /lnd $GO_IMAGE \
   go list -f '{{.Version}}' -m google.golang.org/protobuf)