Encourage usage of latest deployed MCP proxy in Readme.md

[arangatang]

Summary

We want users with uvx to always use the latest version of the code per default, updating the README accordingly.
This is done with the @latest annotation: https://docs.astral.sh/uv/concepts/tools/#tool-versions
If omitted the cached version (which may be outdated) would be used after initial install.

Changes

Update to README

User experience

Customers who follow the readme will always pull latest version from PyPi if following our instructions.

Checklist

If your change doesn't seem to apply, please leave them unchecked.

• I have reviewed the contributing guidelines
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented

Is this a breaking change? (Y/N)

• Yes
• No

Please add details about how this change was tested.

• Did integration tests succeed?
• If the feature is a new use case, is it necessary to add a new integration test case?

Acknowledgment

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