Add support for PHP 7.3

Author: mikeerickson

.travis.yml

@@ -4,6 +4,7 @@ dist: trusty
 php:
   - 7.1
   - 7.2
+  - 7.3
 
 matrix:
   fast_finish: true

composer.json

@@ -28,7 +28,7 @@
   },
   "require-dev": {
     "spatie/phpunit-watcher": "^1.6",
-    "phpunit/phpunit": "7.1.1"
+    "phpunit/phpunit": "7.4.*"
   },
   "autoload": {
     "psr-4": {
@@ -48,4 +48,4 @@
     "test-watch": "vendor/bin/phpunit-watcher watch --testsuite Unit  < /dev/tty",
     "watch-tickets": "vendor/bin/phpunit-watcher watch --testsuite Tickets  < /dev/tty"
   }
-}
+}