Merge pull request #254 from shikorism/feature/php-7.3

DockerfileおよびCI環境をPHP 7.3にアップデート

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2.1
 executors:
   build:
     docker:
-      - image: circleci/php:7.1-node-browsers
+      - image: circleci/php:7.3-node-browsers
         environment:
           APP_DEBUG: true
           APP_ENV: testing

Dockerfile

@@ -1,6 +1,6 @@
 FROM node:10-jessie as node
 
-FROM php:7.1-apache
+FROM php:7.3-apache
 
 ENV APACHE_DOCUMENT_ROOT /var/www/html/public