Feature/support laravel 7 (#4)

* Add support for laravel 7.x
* Update README file

Author: Naveen1895

README.md

@@ -11,7 +11,7 @@
 
 To install this package you will need:
 
- - Laravel >= 6.0
+ - Laravel >= 7.0
  - PHP 7.2+
 
 
@@ -25,7 +25,7 @@ or edit the `composer.json`
 
 ```
 "require": {
-    "linkstreet/laravel-sms": "^5.0"
+    "linkstreet/laravel-sms": "^6.0"
 }
 ```
 

composer.json

@@ -21,7 +21,7 @@
     ],
     "require": {
         "php": ">=7.2",
-        "illuminate/support": "^6.0",
+        "illuminate/support": "^7.0",
         "guzzlehttp/guzzle": "~6.0"
     },
     "autoload": {
@@ -30,8 +30,8 @@
         }
     },
     "require-dev": {
-        "orchestra/testbench": "^4.0",
-        "phpunit/phpunit": "~8.0"
+        "orchestra/testbench": "~5.1.0",
+        "phpunit/phpunit": "~8.5"
     },
     "autoload-dev": {
         "psr-4": {