TypeError: 'str' object does not support item assignment

Processing the CI yaml, some pipelines will fail with 'str' object does not support item assignment when processing the extends keywords

  File "/usr/local/lib/python3.8/site-packages/gitlabemu/runner.py", line 350, in run
    loader.load(fullpath)
  File "/usr/local/lib/python3.8/site-packages/gitlabemu/configloader.py", line 588, in load
    self.config = self._read(filename)
  File "/usr/local/lib/python3.8/site-packages/gitlabemu/configloader.py", line 552, in _read
    objdata = read(filename, **kwargs,
  File "/usr/local/lib/python3.8/site-packages/gitlabemu/configloader.py", line 428, in read
    handle_extends(baseobj)
  File "/usr/local/lib/python3.8/site-packages/gitlabemu/configloader.py", line 491, in do_extends
    return do_extends(baseobj)
  File "/usr/local/lib/python3.8/site-packages/gitlabemu/configloader.py", line 247, in do_extends
    new_obj[item][keyname] = value[keyname]
TypeError: 'str' object does not support item assignment