Update version constraints to support PHP 7.0 and Laravel >= 5.4

Because Laravel Scout 4 is compatible with PHP >= 7.0 and Laravel >= 5.4

Related to: 85de4f2

Author: tortuetorche

composer.json

@@ -20,11 +20,11 @@
         }
     ],
     "require": {
-        "php": ">=7.1.3",
-        "illuminate/contracts": "5.6.*",
-        "illuminate/database": "5.6.*",
-        "illuminate/support": "5.6.*",
-        "laravel/scout": "4.*"
+        "php": ">=7.0",
+        "illuminate/contracts": "~5.4",
+        "illuminate/database": "~5.4",
+        "illuminate/support": "~5.4",
+        "laravel/scout": "~4.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~7.0",