fix test that was assuming wrong return value for getcrashentry

* The test still assumed that Traceback.getcrashentry would return the last element from the traceback when all elements were hidden. However, that was erroneous behavior which was fixed in a583c68e15

testing/code/test_excinfo.py

@@ -311,10 +311,7 @@ class TestTraceback_f_g_h:
         excinfo = pytest.raises(ValueError, f)
         tb = excinfo.traceback
         entry = tb.getcrashentry()
-        co = _pytest._code.Code.from_function(g)
-        assert entry.frame.code.path == co.path
-        assert entry.lineno == co.firstlineno + 2
-        assert entry.frame.code.name == "g"
+        assert entry is None
 
 
 def test_excinfo_exconly():