Update Proxy to golang 1.20 (#150)

diff --git a/core/java8actionloop/CHANGELOG.md b/core/java8actionloop/CHANGELOG.md
index e5c6489..d3b1a33 100644
--- a/core/java8actionloop/CHANGELOG.md
+++ b/core/java8actionloop/CHANGELOG.md
@@ -21,7 +21,7 @@
 # next release
  - use `ibm-semeru-runtimes:open-8u352-b08-jdk-focal` as baseimage
  - update gson version to 2.9.0
-
+ - update Proxy to 1.20 and release 1.21.0
 # 1.19.0
  - Use adoptopenjdk/openjdk8-openj9:x86_64-ubuntu-jdk8u332-b09_openj9-0.32.0
 
diff --git a/core/java8actionloop/Dockerfile b/core/java8actionloop/Dockerfile
index 68d7b8c..9eeddf5 100644
--- a/core/java8actionloop/Dockerfile
+++ b/core/java8actionloop/Dockerfile
@@ -16,7 +16,7 @@
 #
 
 # build go proxy from source
-FROM golang:1.18 AS builder_source
+FROM golang:1.20 AS builder_source
 ARG GO_PROXY_GITHUB_USER=apache
 ARG GO_PROXY_GITHUB_BRANCH=master
 RUN git clone --branch ${GO_PROXY_GITHUB_BRANCH} \
@@ -25,8 +25,8 @@
    mv proxy /bin/proxy
 
 # or build it from a release
-FROM golang:1.18 AS builder_release
-ARG GO_PROXY_RELEASE_VERSION=1.18@1.20.0
+FROM golang:1.20 AS builder_release
+ARG GO_PROXY_RELEASE_VERSION=1.20@1.21.0
 RUN curl -sL \
   https://github.com/apache/openwhisk-runtime-go/archive/{$GO_PROXY_RELEASE_VERSION}.tar.gz\
   | tar xzf -\