Support for Python 3.11

[fabaff]

With Python 3.11 changes were introduced which are breaking the code:

Executing pytestCheckPhase
============================= test session starts ==============================
platform linux -- Python 3.11.3, pytest-7.2.1, pluggy-1.0.0
rootdir: /build/source
plugins: requests-mock-1.10.0
collected 26 items                                                             

test_alpha_vantage/test_alphavantage.py ..............                   [ 53%]
test_alpha_vantage/test_alphavantage_async.py FF.FFFFFFFFF               [100%]

=================================== FAILURES ===================================
_________________ TestAlphaVantageAsync.test_foreign_exchange __________________

args = (<source.test_alpha_vantage.test_alphavantage_async.TestAlphaVantageAsync testMethod=test_foreign_exchange>,)
kwargs = {}

    @wraps(f)
    def test_wrapper(*args, **kwargs):
>       coro = asyncio.coroutine(f)
E       AttributeError: module 'asyncio' has no attribute 'coroutine'

test_alpha_vantage/test_alphavantage_async.py:21: AttributeError
__________________ TestAlphaVantageAsync.test_handle_api_call __________________

args = (<source.test_alpha_vantage.test_alphavantage_async.TestAlphaVantageAsync testMethod=test_handle_api_call>,)
kwargs = {}

    @wraps(f)
    def test_wrapper(*args, **kwargs):
>       coro = asyncio.coroutine(f)
E       AttributeError: module 'asyncio' has no attribute 'coroutine'

test_alpha_vantage/test_alphavantage_async.py:21: AttributeError
[...]

[AlphaVantageSupport]

[2023-07] Temporarily closing this issue due to inactivity.

[fabaff]

@AlphaVantageSupport, please add the commit or PR to the fix. Last change was Dec 25, 2022 thus I highly doubt that this was fixed.