Make about dialog show up as fullscreen on iOS

[ann0see]

Short description of changes Fixes an UI overflow bug for the about dialog on iOS.

Related to: #3343 Now - with some potential device rotations the about dialog can be exited on Qt6:

CHANGELOG: CONDENSE WITH #3343

Context: Fixes an issue?

Related to: #3343

Does this change need documentation? What needs to be documented and how?

No Status of this Pull Request

Ready

What is missing until this pull request can be merged?

Nothing

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