Add message properly

Author: CoolCat467

src/trio/_sync.py

@@ -114,7 +114,10 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    @deprecated
+    @deprecated(
+        "trio.Event.__bool__ is deprecated since Trio 0.31.0, use trio.Event.is_set instead (https://github.com/python-trio/trio/issues/3238)",
+        stacklevel=2,
+    )
     def __bool__(self) -> Literal[True]:
         """Return True and raise warning."""
         warn_deprecated(

test-requirements.in

@@ -8,7 +8,6 @@ trustme               # for the ssl + DTLS tests
 pylint                # for pylint finding all symbols tests
 jedi; implementation_name == "cpython"                  # for jedi code completion tests
 cryptography>=41.0.0  # cryptography<41 segfaults on pypy3.10
-typing_extensions >= 4.15.0
 
 # Tools
 black; implementation_name == "cpython"
@@ -40,3 +39,4 @@ outcome
 sniffio
 # 1.2.1 fixes types
 exceptiongroup >= 1.2.1; python_version < "3.11"
+typing_extensions >= 4.15.0