Update PHP 7.3 runtime to PHP 7.3.12

Author: akrabat

core/php7.3Action/CHANGELOG.md

@@ -18,7 +18,7 @@
 -->
 ## Apache 1.14.0 (next release)
 Changes:
-  - Update version of PHP to 7.3.6
+  - Update version of PHP to 7.3.12
   - Added PHP extension mongodb
   - Support getenv()
 

core/php7.3Action/Dockerfile

@@ -25,7 +25,7 @@ RUN env CGO_ENABLED=0 go get github.com/apache/openwhisk-runtime-go/main && mv /
 #  && cd src/github.com/apache/incubator-openwhisk-runtime-go/main \
 #  && CGO_ENABLED=0 go build -o /bin/proxy
 
-FROM php:7.3.6-cli-stretch
+FROM php:7.3.12-cli-stretch
 
 # install dependencies
 RUN \