Use PHP 7.3 for CircleCI

.circleci/config.yml

@@ -7,7 +7,7 @@ jobs:
   build:
     docker:
       # Specify the version you desire here
-      - image: circleci/php:7.2.3-cli-stretch-node
+      - image: circleci/php:7.3-cli-stretch-node
 
       # Specify service dependencies here if necessary
       # CircleCI maintains a library of pre-built images