Add Laravel 6 support

Author: dmitry-ivanov

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 7.1
   - 7.2
   - 7.3
 

README.md

@@ -15,6 +15,7 @@ Laravel-specific and pure PHP helper functions.
 
 | Laravel | Helper Functions                                                            |
 | ------- | :-------------------------------------------------------------------------: |
+| 6.x     | [6.x](https://github.com/dmitry-ivanov/laravel-helper-functions/tree/6.x)   |
 | 5.8.*   | [5.8.*](https://github.com/dmitry-ivanov/laravel-helper-functions/tree/5.8) |
 | 5.7.*   | [5.7.*](https://github.com/dmitry-ivanov/laravel-helper-functions/tree/5.7) |
 | 5.6.*   | [5.6.*](https://github.com/dmitry-ivanov/laravel-helper-functions/tree/5.6) |

composer.json

@@ -12,22 +12,22 @@
         "email": "[email protected]"
     }],
     "require": {
-        "php": "^7.1.3",
+        "php": "^7.2",
         "ext-dom": "*",
         "ext-json": "*",
         "ext-simplexml": "*",
-        "illuminate/support": "5.8.*",
-        "nesbot/carbon": "^1.26.3 || ^2.0",
-        "symfony/filesystem": "^4.2",
-        "symfony/finder": "^4.2",
-        "symfony/process": "^4.2",
-        "symfony/var-dumper": "^4.2",
+        "illuminate/support": "^6.0",
+        "nesbot/carbon": "^2.0",
+        "symfony/filesystem": "^4.3",
+        "symfony/finder": "^4.3",
+        "symfony/process": "^4.3",
+        "symfony/var-dumper": "^4.3",
         "spatie/array-to-xml": "^2.7"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.5|^8.0",
-        "mockery/mockery": "^1.0",
-        "illuminated/testing-tools": "5.8.*"
+        "phpunit/phpunit": "^8.3",
+        "mockery/mockery": "^1.2",
+        "illuminated/testing-tools": "^6.0"
     },
     "autoload": {
         "files": [