Rasa compatibility issues

[rgstephens]

Under Rasa 2.8.32, the rasa broker script reports the following errors. The is_ready error may be related to use of rasa export:

/opt/venv/lib/python3.8/site-packages/rasa/core/tracker_store.py:946: SADeprecationWarning: Calling URL() directly is deprecated and will be disabled in a future release.  The public constructor for URL is now the URL.create() method.
  return sa.engine.url.URL(
/opt/venv/lib/python3.8/site-packages/rasa/core/brokers/broker.py:118: FutureWarning: The method 'EventBroker.from_endpoint_config' was changed to be 'async'. Your event broker 'dashbot.rasa.rasa' is currently synchronous. Support for synchronous implementations of 'from_endpoint_config' will be removed in 3.0.0.
  rasa.shared.utils.io.raise_deprecation_warning(
Traceback (most recent call last):
  File "/opt/venv/bin/rasa", line 8, in <module>
    sys.exit(main())
  File "/opt/venv/lib/python3.8/site-packages/rasa/__main__.py", line 118, in main
    cmdline_arguments.func(cmdline_arguments)
  File "/opt/venv/lib/python3.8/site-packages/rasa/cli/export.py", line 175, in export_trackers
    rasa.utils.common.run_in_loop(_export_trackers(args))
  File "/opt/venv/lib/python3.8/site-packages/rasa/utils/common.py", line 296, in run_in_loop
    result = loop.run_until_complete(f)
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/opt/venv/lib/python3.8/site-packages/rasa/cli/export.py", line 185, in _export_trackers
    _prepare_event_broker(event_broker)
  File "/opt/venv/lib/python3.8/site-packages/rasa/cli/export.py", line 163, in _prepare_event_broker
    if not event_broker.is_ready():
AttributeError: 'rasa' object has no attribute 'is_ready'