Fix SearchCtrl test by removing checks for TextCtrl methods

Since commit 9eb9497afc ("The new native wxSearchCtrl on GTK does not
include the wxTextCtrl methods, just those from wxTextEntry.") the
methods are no longer part of the SearchCtrl.

unittests/test_srchctrl.py

@@ -48,11 +48,7 @@ class srchctrl_Tests(wtc.WidgetTestCase):
         t = wx.SearchCtrl(self.frame)
         t.Cut
         t.CanCut
-        t.DiscardEdits
-        t.GetDefaultStyle
-        t.GetNumberOfLines
-        t.GetStyle
-        t.IsModified
+        t.IsEditable
         t.HitTest
         t.AppendText
         t.WriteText