FIX: callback endpoint hook

[TauannyFurlanetto]

what

Fixes the TypeError error while using the add_callback_endpoint to BarterDude

Traceback (most recent call last):
  File "/usr/lib64/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib64/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/app/elasticsearch_indexer_worker/__main__.py", line 8, in <module>
    app = Consumer()
  File "/app/elasticsearch_indexer_worker/consumer.py", line 94, in __init__
    (datalake_publisher_mock(), "datalake_publisher")
  File "/usr/local/lib/python3.7/site-packages/barterdude/__init__.py", line 53, in add_callback_endpoint
    hook=hook_to_callback
  File "/usr/local/lib/python3.7/site-packages/barterdude/__init__.py", line 39, in add_endpoint
    )(hook)
  File "/usr/local/lib/python3.7/site-packages/asyncworker/app.py", line 140, in wrapper
    f"handler must be a coroutine: {handler}"
TypeError: handler must be a coroutine: <method-wrapper '__call__' of function object at 0x400c8db830>

Also fixes the typing error caused by type checking the hook_to_callback function and the error caused by not awaiting the _call_callback_endpoint coroutine

why

Without this is fix, we can't run apps with callback hooks

how

Makes the hook_to_callback function a couroutine, adds a typing to the hook_to_callback args and awaits for the _call_callback_endpoint func