added repo variables test

Author: SergkeiM

test/Github/Tests/Api/RepoTest.php

@@ -570,6 +570,16 @@ public function shouldGetReleasesApiObject()
         $this->assertInstanceOf(\Github\Api\Repository\Releases::class, $api->releases());
     }
 
+    /**
+     * @test
+     */
+    public function shouldGetVariablesApiObject()
+    {
+        $api = $this->getApiMock();
+
+        $this->assertInstanceOf(\Github\Api\Repository\Actions\Variables::class, $api->variables());
+    }
+
     /**
      * @test
      */