Update Proxy to golang 1.20 (#130)

diff --git a/core/php8.1Action/CHANGELOG.md b/core/php8.1Action/CHANGELOG.md
index 86530ee..05c874c 100644
--- a/core/php8.1Action/CHANGELOG.md
+++ b/core/php8.1Action/CHANGELOG.md
@@ -21,6 +21,8 @@
 PHP 8 as new features and some incompatiblities. See [migration guide](https://www.php.net/manual/en/migration80.php) for more information.
 
 ## Next Release
+- Used openwhisk-runtime-go 1.20.0 to build proxy
+
 Initial release
 
 - Added: PHP: 8.1.9
diff --git a/core/php8.1Action/Dockerfile b/core/php8.1Action/Dockerfile
index d06e034..6642cbd 100644
--- a/core/php8.1Action/Dockerfile
+++ b/core/php8.1Action/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 -\