Update to PHP 7.3.1 (#52)

diff --git a/core/php7.3Action/CHANGELOG.md b/core/php7.3Action/CHANGELOG.md
index 4357aa6..59b4bbb 100644
--- a/core/php7.3Action/CHANGELOG.md
+++ b/core/php7.3Action/CHANGELOG.md
@@ -20,7 +20,7 @@
 ## Apache 1.13.0-incubating (next release)
 Initial release
 
-- Added: PHP: 7.3.0
+- Added: PHP: 7.3.1
 - Added: PHP extensions in addition to the standard ones:
     - bcmath
     - curl
diff --git a/core/php7.3Action/Dockerfile b/core/php7.3Action/Dockerfile
index 85c7801..a412851 100644
--- a/core/php7.3Action/Dockerfile
+++ b/core/php7.3Action/Dockerfile
@@ -17,7 +17,7 @@
 
 FROM openwhisk/actionloop:410d006 as builder
 
-FROM php:7.3.0-cli-stretch
+FROM php:7.3.1-cli-stretch
 
 # install dependencies
 RUN \