Backups fail if port is changed

Changing the default port from 3000 will cause the backup script to fail:
root@grafana-3:/etc/cron.d# /usr/local/bin/dashboards_backup -d /srv/backups <redacted>
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 141, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 83, in create_connection
    raise err
  File "/usr/lib/python3/dist-packages/urllib3/util/connection.py", line 73, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 601, in urlopen
    chunked=chunked)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 357, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.6/http/client.py", line 1264, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1310, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1259, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1038, in _send_output
    self.send(msg)
  File "/usr/lib/python3.6/http/client.py", line 976, in send
    self.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 166, in connect
    conn = self._new_conn()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 150, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7fe4aa961e10>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/requests/adapters.py", line 440, in send
    timeout=timeout
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 639, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 398, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='localhost', port=3000): Max retries exceeded with url: /api/org (Caused by NewConnectionError('<urllib3.connection.HTTPConnection objec
t at 0x7fe4aa961e10>: Failed to establish a new connection: [Errno 111] Connection refused',))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/dashboards_backup", line 42, in <module>
    main(args)
  File "/usr/local/bin/dashboards_backup", line 24, in main
    org_name = requests.get(base_url+'org', headers=headers).json()['name']
  File "/usr/lib/python3/dist-packages/requests/api.py", line 72, in get
    return request('get', url, params=params, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/api.py", line 58, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/sessions.py", line 520, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/lib/python3/dist-packages/requests/sessions.py", line 630, in send
    r = adapter.send(request, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/adapters.py", line 508, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='localhost', port=3000): Max retries exceeded with url: /api/org (Caused by NewConnectionError('<urllib3.connection.HTTPConnection ob
ject at 0x7fe4aa961e10>: Failed to establish a new connection: [Errno 111] Connection refused',))

This seems to be caused from https://git.launchpad.net/charm-grafana/tree/src/files/dashboards_backup#n21

def main(args):
    base_url = 'http://localhost:3000/api/'

Changing the port in base_url to the updated port does resolve the error.