update phpunit dependencies

Author: arkadiusjonczek

README.md

@@ -4,6 +4,8 @@ Simple PHP Library for DeepL API.
 
 ## Installation
 
+Use composer if you want to use this library in your project.
+
 ```bash
 composer require babymarkt/deepl
 ```
@@ -21,14 +23,26 @@ print_r($result);
 
 ## Tests
 
-First, create phpunit.xml from dist file.
+Clone the repository.
+
+```bash
+git clone git@github.com:Baby-Markt/deepl-php-lib.git
+```
+
+Create phpunit.xml from dist file.
 
 ```bash
 cp phpunit.xml.dist phpunit.xml
 ```
 
-Now, run PHPUnit Tests.
+Install composer dependencies.
 
+```bash
+composer install
 ```
-php phpunit-4.8.phar
+
+Now, run PHPUnit Tests.
+
+```bash
+vendor/bin/phpunit
 ```

composer.json

@@ -14,7 +14,7 @@
     },
     "require-dev": {
         "php": ">=5.3",
-        "phpunit/phpunit": "4.8"
+        "phpunit/phpunit": "^4.8"
     },
     "autoload": {
         "psr-4": {