Remove redundant uvicorn[standard] from optional-dependencies.

[omprakash7218]

Removes the redundant uvicorn[standard] >= 0.15.0 entry from
[project.optional-dependencies].standard in pyproject.toml.

uvicorn[standard] is already a mandatory dependency (listed under
dependencies), so listing it again under the optional "standard" group
is redundant and can mislead readers into thinking it's only installed
when the optional extra is requested.

Follow-up to the remaining item raised in
#171

AI Disclaimer

Used Claude (Anthropic) to help understand the pyproject.toml structure
(dependencies vs optional-dependencies) , since this is my first open source
contribution. The actual identification of the issue was already
reported by @BhuwanPandey in the linked discussion; my contribution is
just implementing the one-line fix.

Checklist

• This PR links to a GitHub Discussion for the proposed code change.
• I added tests for the change.
• The new or updated tests fail on the main branch and pass on this PR.
• Coverage stays at 100%.
• The documentation explains the change if needed.

[github-actions]

This PR modifies dependency files (pyproject.toml or uv.lock), which is restricted to members of the fastapi organization on GitHub.

If you need a dependency change, please open a discussion describing what you need and why.

Closing this PR automatically.