[Tests] Fixed broken tests on PHP 5.3

Tests were broken due usage of short array syntax.

Author: vimishor

CHANGELOG.md

@@ -6,6 +6,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed:
   - Updated broken links (_.org to .io_) inside README.md
+  - Fixed broken tests on PHP 5.3 due to short array syntax.
 
 ## 0.8.3 / 2017-05-15
 

test/Bitbucket/Tests/API/Http/ClientTest.php

@@ -207,8 +207,8 @@ private function getListenerMock($name = 'dummy')
 
     public function invalidApiVersionsProvider()
     {
-        return [
-            ['3.1'], ['1,2'], ['1,0'], ['2.1'], ['4'], [2], ['string'], [2.0]
-        ];
+        return array(
+            array('3.1'), array('1,2'), array('1,0'), array('2.1'), array('4'), array(2), array('string'), array(2.0)
+        );
     }
 }