chore(deps): upgrade dependencies to resolve security vulnerabilities

Dependabot flagged 20 security alerts in transitive dependencies,
including high-severity issues in urllib3, mcp, aiohttp, and starlette.

Running `uv lock --upgrade` updates the lock file to pull in patched
versions. The key updates are urllib3 2.4.0 to 2.6.3, mcp 1.7.1 to
1.26.0, and starlette 0.46.2 to 0.52.1. The aiohttp dependency was
removed entirely as it's no longer required by the newer mcp version.

[1]: https://github.com/stefanoamorelli/sec-edgar-mcp/security/dependabot

Author: stefanoamorelli