Less suspicious user agent

Updates the user agent string to a less problematic one, fixes issue #17 .

src/Favicon/DataAccess.php

@@ -42,7 +42,7 @@ private function setContext()
                     'max_redirects' => 1,
                     'timeout' => 10,
                     'header' => 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:20.0; Favicon; ' .
-                                '+https://github.com/ArthurHoaro/favicon) Gecko/20100101 Firefox/32.0\r\n',
+                                '+https://github.com/ArthurHoaro/favicon) Gecko/20100101 Firefox/78.0',
                 ]
             ]
         );