Add per-task ack type support

[vvanglro]

Summary

• Add per-task ack_type support via task labels, overriding worker-level --ack-type when present.
• Support both string values and AcknowledgeType enum values for task-level ack configuration.
• Export AcknowledgeType from taskiq and document the new per-task usage.

Related discussion: https://github.com/orgs/taskiq-python/discussions/635

Testing

• uv run pytest tests/receiver/test_receiver.py -q
• uv run ruff check taskiq/acks.py taskiq/receiver/receiver.py taskiq/__init__.py tests/receiver/test_receiver.py
• uv run mypy taskiq
• uv run pytest -q -x --ignore=tests/opentelemetry
• uv run pytest tests/opentelemetry -q

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.02%. Comparing base (9f8db96) to head (2bdde8f).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #636      +/-   ##
==========================================
+ Coverage   79.79%   80.02%   +0.22%     
==========================================
  Files          69       69              
  Lines        2529     2548      +19     
==========================================
+ Hits         2018     2039      +21     
+ Misses        511      509       -2     

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[s3rius]

The request looks good, however, can you please fix tests and simplify parse_acknowledge_type function?

[s3rius]

All looks good. Thanks for contributions!