fix: remove empty file: chatwidget_stream_tests.rs (#3356)

Originally added in https://github.com/openai/codex/pull/2029.

codex-rs/tui/src/chatwidget_stream_tests.rs

@@ -1 +0,0 @@
-

codex-rs/tui/src/lib.rs

@@ -61,11 +61,6 @@ mod user_approval_widget;
 mod version;
 mod wrapping;
 
-// Internal vt100-based replay tests live as a separate source file to keep them
-// close to the widget code. Include them in unit tests.
-#[cfg(test)]
-mod chatwidget_stream_tests;
-
 #[cfg(not(debug_assertions))]
 mod updates;