Update Laravel and PHP version requirements

Author: mskochev

.travis.yml

@@ -1,6 +1,7 @@
 language: php
 php:
-- 5.6
+- '7.1'
+- '7.2'
 before_install:
 - composer install --dev -v --prefer-source
 script:

composer.json

@@ -23,17 +23,17 @@
         }
     ],
     "require": {
-        "php": ">=5.6.4",
-        "laravel/framework": "5.4.*",
+        "php": ">=7.1.3",
+        "laravel/framework": "5.6.*",
         "laravel/tinker": "~1.0",
         "mailjet/mailjet-apiv3-php": "^1.2",
-        "mailjet/mailjet-swiftmailer": "^1.0"
+        "mailjet/mailjet-swiftmailer": "^2.0"
     },
     "require-dev": {
         "fzaninotto/faker": "~1.4",
         "mockery/mockery": "0.9.*",
-        "phpunit/phpunit": "~5.7",
-        "orchestra/testbench": "~3.4"
+        "phpunit/phpunit": "~7.0",
+        "orchestra/testbench": "3.6"
     },
     "autoload": {
         "psr-4": {