test: silence legacy pytest return-value warnings

[harvatechs]

Motivation

• Reduce noisy CI/test output by suppressing PytestReturnNotNoneWarning emitted by legacy script-style tests that intentionally return booleans instead of using assert.

Description

• Add a repository-level pytest.ini containing a filterwarnings rule to ignore the specific PytestReturnNotNoneWarning (file: pytest.ini).

Testing

• Ran the full test suite with pytest -q, which completed successfully with 30 passed, 2 skipped.

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Codex Task