Include optional params parameter for Commits compare

With the current API, we cannot paginate compare basehead function call. The Github API limits the response to only 250 commits so for larger diffs we have no option.

Author: mountiny

lib/Github/Api/Repository/Commits.php

@@ -16,14 +16,14 @@ public function all($username, $repository, array $params)
         return $this->get('/repos/'.rawurlencode($username).'/'.rawurlencode($repository).'/commits', $params);
     }
 
-    public function compare($username, $repository, $base, $head, $mediaType = null)
+    public function compare($username, $repository, $base, $head, $mediaType = null, array $params = [])
     {
         $headers = [];
         if (null !== $mediaType) {
             $headers['Accept'] = $mediaType;
         }
 
-        return $this->get('/repos/'.rawurlencode($username).'/'.rawurlencode($repository).'/compare/'.rawurlencode($base).'...'.rawurlencode($head), [], $headers);
+        return $this->get('/repos/'.rawurlencode($username).'/'.rawurlencode($repository).'/compare/'.rawurlencode($base).'...'.rawurlencode($head), $params, $headers);
     }
 
     public function show($username, $repository, $sha)