Update to PHP 7.3 (#452)

Author: driesvints

.circleci/config.yml

@@ -2,7 +2,7 @@ version: 2
 jobs:
   build:
     docker:
-      - image: circleci/php:7.2-node-browsers
+      - image: circleci/php:7.3-node-browsers
     working_directory: ~/repo
     steps:
       - checkout

composer.json

@@ -4,7 +4,7 @@
     "license": "MIT",
     "type": "project",
     "require": {
-        "php": "^7.2",
+        "php": "^7.3",
         "bugsnag/bugsnag-laravel": "^2.14",
         "doctrine/dbal": "^2.5",
         "facade/ignition": "^1.0",
@@ -82,4 +82,4 @@
     },
     "minimum-stability": "dev",
     "prefer-stable": true
-}
+}