Updating to grpc 1.13.1

- and make value a parameter

Change-Id: Ib1b6cc23aeac98f3c177f81254bc455c16086875
diff --git a/Makefile b/Makefile
index 15664eb..dd5b86e 100644
--- a/Makefile
+++ b/Makefile
@@ -26,6 +26,7 @@
 PROTOC_SHA256SUM                ?= "a1b8ed22d6dc53c5b8680a6f1760a305b33ef471bece482e92728f00ba2a2969"
 PROTOC_GEN_GO_VERSION           ?= "1.3.2"
 PROTOC_GEN_GRPC_GATEWAY_VERSION ?= "1.14.3"
+PROTOC_GEN_CPP_VERSION          ?= "1.3.1"
 
 # Docker related
 DOCKER_LABEL_VCS_DIRTY     = false
@@ -120,6 +121,7 @@
 	--build-arg PROTOC_SHA256SUM=${PROTOC_SHA256SUM} \
 	--build-arg PROTOC_GEN_GO_VERSION=${PROTOC_GEN_GO_VERSION} \
 	--build-arg PROTOC_GEN_GRPC_GATEWAY_VERSION=${PROTOC_GEN_GRPC_GATEWAY_VERSION} \
+	--build-arg PROTOC_GEN_CPP_VERSION=${PROTOC_GEN_CPP_VERSION} \
 	-t ${IMAGENAME}:${DOCKER_TAG}-protoc \
 	-t ${IMAGENAME}:latest-protoc \
 	-f docker/protoc.Dockerfile .
diff --git a/VERSION b/VERSION
index 437459c..73462a5 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.5.0
+2.5.1
diff --git a/docker/protoc.Dockerfile b/docker/protoc.Dockerfile
index 9965969..c60c02d 100644
--- a/docker/protoc.Dockerfile
+++ b/docker/protoc.Dockerfile
@@ -34,19 +34,23 @@
     unzip /tmp/protoc-${PROTOC_VERSION}-linux-x86_64.zip -d /tmp/protoc3 && \
     chmod -R a+rx /tmp/protoc3/
 
-FROM alpine:3.13 as cpp-build
+ARG GOLANG_VERSION
+FROM golang:$GOLANG_VERSION-alpine3.13 as cpp-build
+
+ARG PROTOC_GEN_CPP_VERSION
 
 # Install required packages
 RUN apk add --no-cache \
     build-base=0.5-r2 \
     git=2.30.2-r0 \
     cmake=3.18.4-r1 \
-    linux-headers=5.7.8-r0
+    linux-headers=5.7.8-r0 \
+    perl=5.32.0-r0
 
 WORKDIR /src
 
 # Clone grpc and submodules
-RUN git clone --recurse-submodules -b v1.31.0 \
+RUN git clone --recurse-submodules -b v${PROTOC_GEN_CPP_VERSION} \
         --depth=1 --shallow-submodules https://github.com/grpc/grpc
 
 # Create and configure make environment