[Misc] Update typechecking in example_online/text_to_image

[Lucaskabela]

Purpose

Updates typechecking to pass with mypy when ran locally for this example_online/text_to_image directory

Test Plan

mypy examples/online_serving/text_to_image/

Test Result

Before

pyproject.toml: [mypy]: python_version: Invalid python version '3.12, 3.13' (expected format: 'x.y')
examples/online_serving/text_to_image/openai_chat_client.py:90: error: Function is missing a return type annotation  [no-untyped-def]
examples/online_serving/text_to_image/openai_chat_client.py:90: note: Use "-> None" if function does not return a value
examples/online_serving/text_to_image/gradio_demo.py:42: error: Incompatible types in assignment (expression has type "str", target has type "float")  [assignment]
examples/online_serving/text_to_image/gradio_demo.py:74: error: Function is missing a return type annotation  [no-untyped-def]
examples/online_serving/text_to_image/gradio_demo.py:172: error: Function is missing a return type annotation  [no-untyped-def]
examples/online_serving/text_to_image/gradio_demo.py:172: note: Use "-> None" if function does not return a value
Found 4 errors in 2 files (checked 2 source files)

After

Success: no issues found in 2 source files

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[Lucaskabela]

cc @Gaohan123 for review as well

[Copilot]

Pull request overview

This PR updates type annotations in the examples/online_serving/text_to_image directory to ensure mypy type checking passes when run locally. The changes address mypy configuration issues and add missing type annotations to functions and variables.

Changes:

• Fixed mypy Python version configuration from invalid "3.12, 3.13" to valid "3.12"
• Added type annotations to function signatures and local variables in example scripts
• Added necessary typing imports to support type annotations

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
pyproject.toml	Corrected python_version in mypy configuration from "3.12, 3.13" to "3.12"
examples/online_serving/text_to_image/openai_chat_client.py	Added type annotations for variables and main() function, imported typing.Any
examples/online_serving/text_to_image/gradio_demo.py	Added type annotations for extra_body dict, return types for create_demo() and main(), and modified Gradio Blocks instantiation pattern

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[Copilot]

The pattern of separating the Gradio Blocks instantiation from the context manager is inconsistent with other similar files in the codebase. For example, examples/offline_inference/text_to_image/gradio_demo.py uses with gr.Blocks(...) as demo: and also has a return type annotation of -> gr.Blocks. Consider using the more conventional pattern with gr.Blocks(title="Qwen-Image Demo") as demo: which would be consistent with the rest of the codebase and should also pass mypy type checking.

[Lucaskabela]

If we return that, demo would not be in scope for the return statement at the end of the function though right?