Add SmolLM3

[anton-l]

What does this PR do?

Adds the SmolLM3 modular arch

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• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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[HuggingFaceDocBuilderDev]

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[Copilot]

Pull Request Overview

This PR introduces the new SmolLM3 modular architecture, adding model implementations, configuration, integration with the auto-model system, tests, and documentation.

• Added SmolLM3 configuration and model modules in src/transformers/models/smollm3
• Extended auto-model routing to support SmolLM3 in the auto configuration and modeling modules
• Introduced a dedicated test suite and documentation for SmolLM3

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
utils/check_config_attributes.py	Added config attribute for SmolLM3Config
tests/models/smollm3/test_modeling_smollm3.py	New test suite for SmolLM3 functionality
src/transformers/models/smollm3/modular_smollm3.py	New implementation modules for SmolLM3 including its attention layer
src/transformers/models/smollm3/configuration_smollm3.py	New configuration for SmolLM3, auto-generated from the modular file
src/transformers/models/smollm3/init.py	Updated module export for SmolLM3
src/transformers/models/auto/modeling_auto.py	Registered SmolLM3 model classes in the auto-model system
src/transformers/models/auto/configuration_auto.py	Registered SmolLM3 configuration in the auto-model system
docs/source/en/model_doc/smollm3.md	Documentation page for the SmolLM3 model
docs/source/en/_toctree.yml	Added SmolLM3 to the documentation tree

Comments suppressed due to low confidence (2)

docs/source/en/model_doc/smollm3.md:53

• [nitpick] The code snippet accesses 'generated_text' with a list index and then a 'content' key, which may be unclear. Please clarify the expected structure of the pipeline output in the documentation or adjust the snippet to match the actual return format.

print(outputs[0]["generated_text"][-1]['content'])

src/transformers/models/smollm3/configuration_smollm3.py:1

• [nitpick] Consider simplifying or removing the repetitive alarm emojis in the header to maintain a professional appearance in the auto-generated file.

#                🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨

[ArthurZucker]

Well done! Only TODO for the readme the rest is neat!

[ArthurZucker]

you just need to run the creation of the modeling file from moudlar to get the CIs green!