fix: Don't warn that KinoLiveComponent import is unused

[joshlarson]

Removes this warning, which shows up in any and all test output:

     warning: unused import KinoLiveComponent.Plug
     │
 264 │   import KinoLiveComponent.Plug, only: [allow_insecure_connection: 2]
     │   ~
     │
     └─ lib/dotcom_web/router.ex:264:3

The import is actually used (in :dev and :dev only), but something about the if Mix.env() == :dev check means that when Mix.env() is :test, it thinks that the import isn't.

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No ticket.