deps(amazonq): Update mynah-ui to 4.18.1

[jpinkney-aws]

Problem

• Partner teams need the newer version of mynah UI that solves a couple ux problems:

• File details and name unnecessary crop
• Chat container exceeds width of panel

Solution

• Update mynah ui

Release notes: https://github.com/aws/mynah-ui/releases/tag/v4.18.1

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License: I confirm that my contribution is made under the terms of the Apache 2.0 license.