UI: Fix window text when disabled in dark theme

[shiina424]

Description

Fixed dark theme text. If this is incorrect, we would appreciate it if you could correct it.

Before

After

Motivation and Context

I want displayed correctly.

How Has This Been Tested?

I changed the qss file and tested it.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[RytoEX]

Please provide updated screenshots so that we can reevaluate this PR.

[RytoEX]

Here are updated "after" screenshots after applying the change locally:

[shiina424]

@RytoEX I just noticed this. Sorry I could not provide screenshots. Thanks for the screenshot.