Filter triton AnnAssign DeprecationWarning on Python 3.14

[albertvillanova]

This PR silences a DeprecationWarning emitted across many test modules in CI on Python 3.14 by Triton's kernel compiler.

I reported upstream at:

• ast.AnnAssign built without required simple field in visit_FunctionDef (DeprecationWarning on Python 3.14, error on 3.15) triton-lang/triton#10981 (not yet fixed).

Removal is tracked in:

• Remove triton AnnAssign warning filter once triton ships the fix #6466.

Note that on Python 3.15 this becomes a hard error the filter will not suppress, so Triton must be fixed/upgraded before then.

Motivation

Compiling @triton.jit kernels during tests triggers, on Python 3.14:

triton/compiler/code_generator.py:629: DeprecationWarning: AnnAssign.__init__ missing 1 required positional argument: 'simple'. This will become an error in Python 3.15.
  init_node = ast.AnnAssign(target=st_target, value=default_value, annotation=annotation)

Triton builds an ast.AnnAssign node without the required simple field (in visit_FunctionDef, for kernel arguments that have both an annotation and a default value). The warning comes from Triton, not TRL, and is triggered only indirectly by kernel compilation. It appears in tests/test_grpo_trainer.py, tests/test_kto_trainer.py, tests/test_dpo_trainer.py, tests/test_rloo_trainer.py, tests/test_sft_trainer.py, and tests/test_utils.py.

Solution

Following the existing precedent in pyproject.toml, filter the non-actionable upstream warning. The match stops before the colon in the message (AnnAssign.__init__ missing 1 required positional argument) so it stays a valid pytest filter spec and specific to this deprecation.

Changes

• Add a filterwarnings entry in pyproject.toml to ignore Triton's AnnAssign simple-field DeprecationWarning

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Note

Low Risk
Test configuration only; no production code paths change, though reliance on the filter will break on Python 3.15 if Triton remains unfixed.

Overview
Adds a pytest filterwarnings entry in pyproject.toml so CI on Python 3.14 no longer fails or floods logs when tests indirectly compile Triton kernels.

The ignored message is Triton’s upstream ast.AnnAssign missing simple DeprecationWarning (documented with tracking issue #6466 and triton-lang/triton#10981), matching the same pattern as existing filters for Liger, bitsandbytes, and PyTorch.

This is a test/CI hygiene change only; runtime TRL behavior is unchanged. Note that the warning is expected to become a hard error on Python 3.15, so the filter is temporary until Triton is fixed or upgraded.

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[bot-ci-comment]

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