Olmo 3 tool parser and tests

[pdasigi]

Purpose

This PR adds a tool parser for parsing the function calls made by the Olmo 3 model. Support for the model has already been merged (#24534). Olmo 3 outputs function calls in the following format

<function_calls>function1(arg1=value1)\nfunction2(arg2=value2)</function_calls>

This format is similar to the one that the existing Pythonic parser expects except for the presence of xml tags and function calls being delimited by newline characters instead of being represented as a list within brackets.

Test Plan

This PR also includes tests. Existing tests have not been modified or will be impacted.

Test Result

pytest tests/entrypoints/openai/tool_parsers/test_olmo3_tool_parser.py

Output:

========================================================================= test session starts ==========================================================================
platform darwin -- Python 3.11.13, pytest-8.4.2, pluggy-1.6.0
rootdir: /Users/pradeepd/workspace/vllm
configfile: pyproject.toml
plugins: anyio-4.10.0
collected 20 items                                                                                                                                                     

tests/entrypoints/openai/tool_parsers/test_olmo3_tool_parser.py ....................                                                                             [100%]

========================================================================== 20 passed in 1.67s ==========================================================================

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request introduces a tool parser for the Olmo 3 model, along with a comprehensive set of tests. The implementation correctly handles the specific format of Olmo 3's function calls, including XML tags, newline delimiters, and non-Pythonic literals like null, true, and false. The tests are well-structured and cover a wide range of scenarios for both streaming and non-streaming modes. My main feedback is regarding significant code duplication between the new Olmo3PythonicToolParser and the existing PythonicToolParser. Refactoring this into a shared base class would greatly improve maintainability.

[mergify]

Documentation preview: https://vllm--26143.org.readthedocs.build/en/26143/

[pdasigi]

@chaunceyjiang I addressed the comments you made. Can you please take a look again. Thanks!

[chaunceyjiang]

Thanks~