fix: Function call syntax error

[BulkBeing]

Fix a syntax error.

Also, the type of request_iterator in grpc streaming is an AsyncIterator, not AsyncIterable (https://grpc.io/docs/languages/python/basics/#request-streaming-rpc). We call __anext__ in the body (if it was AsyncIterable, it should have been request_iterator.__aiter__().__anext__() or anext(aiter(generator_response)) in Python > 3.10.

I'm also changing return type to be AsyncIterator (from AsyncIterable). Functionally, both are same and users shouldn't see any issues. The AsyncIterator is more restrictive, and is exhausted once iterated over. AsyncIterable indicates that the iterator can be created any number of times by calling aiter(obj).

[vigith]

Tests are failing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.69%. Comparing base (ac2b513) to head (dfa4d94).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #251      +/-   ##
==========================================
+ Coverage   93.62%   93.69%   +0.06%     
==========================================
  Files          65       65              
  Lines        2888     2888              
  Branches      152      152              
==========================================
+ Hits         2704     2706       +2     
+ Misses        134      132       -2     
  Partials       50       50              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[kohlisid]

Nit: @BulkBeing could you also update and check the _dytes typing that we use accordingly then?
eg: https://github.com/numaproj/numaflow-python/blob/main/pynumaflow/reducer/_dtypes.py#L354