refactor: Remove unused variable on dialogue_view_test.dart

[luanpotter]

Description

Fix existing issue detect by GitHub's ever-evolving automated analysis:

Checklist

• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

[spydon]

I would rather suppress this warning and add a TODO, this seems like a nice feature to have once it is built all the way to the user

[luanpotter]

Hum but this is a private class used one-off on a test file? So should not affect any user whatsoever right? Or am I missing something?

[spydon]

Hum but this is a private class used one-off on a test file? So should not affect any user whatsoever right? Or am I missing something?

Aah, you're right, approved!