Tests/LibWeb: Remove duplicate "headers" property in HTTP echo request

Author: https://github.com/rmg-x
Commit: https://github.com/LadybirdBrowser/ladybird/commit/e4bc6178b93
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2802
Reviewed-by: https://github.com/tcl3 ✅

Tests/LibWeb/Fixtures/http-test-server.py

@@ -25,7 +25,6 @@ class Echo:
     headers: Dict[str, str] | None
     body: str | None
     delay_ms: int | None
-    headers: dict | None
 
 
 # In-memory store for echo responses