refactor(tokenizer): remove dead to_dict override

[AmitMY]

Audit item #6, now confirmed rather than suspected.

-    def to_dict(self):
-        return {}

Why it is dead

• No caller. Nothing in the repo calls tokenizer.to_dict() — the one .to_dict() in the codebase is config.to_dict() on a PretrainedConfig, unrelated.
• It overrides nothing. There is no to_dict anywhere in the PreTrainedTokenizer MRO, so it was not shadowing a base method whose behaviour needed neutralising. Deleting it leaves the attribute genuinely absent, not falling back to something else.
• Nothing in transformers calls it on a tokenizer. Grepped the installed package across top-level modules, integrations/, trainer*.py and modelcard.py.

Verified on both CI transformers versions

With and without the method, on 4.57.6 and 5.14.1:

check	with	without
save_pretrained + AutoTokenizer.from_pretrained round trip	OK	OK
apply_chat_template	OK	OK
__call__	OK	OK
repr	OK	OK

241 passed on both versions. ruff clean.

Caveat worth a reviewer's judgement

Commit 33c7f1a "fix(tokenizer): dict should be empty" added this deliberately, and the message does not say what it fixed. My checks cover transformers itself; if it was working around a downstream consumer — wandb config logging, datasets fingerprinting, something in the training script — those paths are not exercised here. If you remember what prompted that commit and it was outside transformers, say so and I will close this.

🤖 Generated with Claude Code

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Note

Low Risk
Deletes dead code with no references in-repo; only residual risk is an undocumented downstream consumer of the old empty to_dict.

Overview
Removes the UTFTokenizer.to_dict() override that only returned {}, as audit item #6.

The method had no callers in this repo (unlike config.to_dict() on PretrainedConfig), did not override anything on the PreTrainedTokenizer MRO, and tokenizer round-trips (save_pretrained / AutoTokenizer, apply_chat_template, __call__) were checked on transformers 4.57.6 and 5.14.1 with the method removed.

Reviewer note: commit 33c7f1a added this deliberately; if something outside transformers (e.g. wandb, datasets fingerprinting) relied on it, that path is not covered by the checks above.

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