add "permission" param to repo.add_collaborator

Author: kuepe-sl

src/github3/repos/repo.py

@@ -118,13 +118,16 @@ def _create_pull(self, data):
         return self._instance_or_null(pulls.ShortPullRequest, json)
 
     @decorators.requires_auth
-    def add_collaborator(self, username):
+    def add_collaborator(self, username, permission=None):
         """Add ``username`` as a collaborator to a repository.
 
         :param username:
             (required), username of the user
         :type username:
             str or :class:`~github3.users.User`
+        :param str permission:
+            (optional), permission to grant the collaborator, valid on organization repositories only
+            Can be 'pull', 'triage', 'push', 'maintain', 'admin' or an organization-defined custom role name.
         :returns:
             True if successful, False otherwise
         :rtype:
@@ -134,7 +137,12 @@ def add_collaborator(self, username):
         url = self._build_url(
             "collaborators", str(username), base_url=self._api
         )
-        return self._boolean(self._put(url), 201, 404)
+        if permission:
+            data = {"permission": permission}
+            resp = self._put(url, data=jsonlib.dumps(data))
+        else:
+            resp = self._put(url)
+        return self._boolean(resp, 201, 404)
 
     def archive(self, format, path="", ref="master"):
         """Get the tarball or zipball archive for this repo at ref.