[gtk/tests-cleanup] tests: Drop testdnd3

[Matthias Clasen <matthiasc src gnome org>]

commit dcfb4690c32780a8c5e27845481309af70153cb7
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu May 14 20:32:53 2020 -0400

    tests: Drop testdnd3
    
    This has been integrated in gtk4-demo as the
    DND example.
    
    See #2738

 tests/meson.build |   1 -
 tests/testdnd3.c  | 326 ------------------------------------------------------
 2 files changed, 327 deletions(-)
---
diff --git a/tests/meson.build b/tests/meson.build
index 5b4b5603d3..5cb5a04d92 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -25,7 +25,6 @@ gtk_tests = [
   ['testdialog'],
   ['testdnd'],
   ['testdnd2'],
-  ['testdnd3'],
   ['testellipsise'],
   ['testentrycompletion'],
   ['testentryicons'],