fix: allow non-localhost connections by configuring trusted_hosts

[VedantMadane]

Fixes #89: 421 Misdirected Request error when accessing MCP server via IP address

When the server is configured with --host 0.0.0.0 (which allows connections from any interface), uvicorn's Host header validation would reject requests made via IP address because the trusted_hosts list wasn't configured to accept them.

This fix adds uvicorn_kwargs configuration to allow any valid Host header when the server is bound to all interfaces (0.0.0.0), enabling access from both localhost and IP addresses in Kubernetes and other containerized environments.

Testing

• Server started with --host 0.0.0.0 --port 8000
• ✅ Connections via localhost work
• ✅ Connections via IP address (172.16.x.x) now work
• ✅ Custom Host headers are allowed

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[VedantMadane]

Friendly bump -- this PR is still mergeable and ready for review. Let me know if anything needs updating.

[alansfyeung]

@VedantMadane I tried running your proposed fix but it doesn't work. (Python 3.12)

---

What did work was an approach that set the flag to false - obviously not an elegant or final solution.

    # When host is "0.0.0.0", we need to allow any valid connection
    if host == "0.0.0.0" and mcp.settings.transport_security:
        mcp.settings.transport_security.enable_dns_rebinding_protection = False

Other projects are adding env vars for allowed hosts, etc. as documented in modelcontextprotocol/python-sdk#1798
so that approach can also be done for this repo