gpui: Fix visual_test.rs feature-gating screen-capture import (#49701)

Closes #ISSUE

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- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [ ] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- N/A

crates/gpui/src/platform/visual_test.rs

@@ -5,7 +5,6 @@
 //! - Deterministic task scheduling via TestDispatcher
 //! - Controllable time via `advance_clock`
 
-#[cfg(feature = "screen-capture")]
 use crate::ScreenCaptureSource;
 use crate::{
     AnyWindowHandle, BackgroundExecutor, ClipboardItem, CursorStyle, ForegroundExecutor, Keymap,