Handle no remote

[pawamoy]

Handle this a bit more nicely:

  Traceback (most recent call last):
    ...
    File "/home/pawamoy/.cache/pypoetry/virtualenvs/pawamoy-testing-MLPX4Zaj-py3.8/lib/python3.8/site-packages/git_changelog/build.py", line 145, in __init__
      remote_url = self.get_remote_url()
    File "/home/pawamoy/.cache/pypoetry/virtualenvs/pawamoy-testing-MLPX4Zaj-py3.8/lib/python3.8/site-packages/git_changelog/build.py", line 206, in get_remote_url
      check_output(["git", "config", "--get", "remote.origin.url"], cwd=self.repository)  # nosec
    File "/usr/lib/python3.8/subprocess.py", line 411, in check_output
      return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
    File "/usr/lib/python3.8/subprocess.py", line 512, in run
      raise CalledProcessError(retcode, process.args,
  subprocess.CalledProcessError: Command '['git', 'config', '--get', 'remote.origin.url']' returned non-zero exit status 1.