patch 8.1.1831: confusing skipped message

Problem:    Confusing skipped message.
Solution:   Drop "run" from "run start the GUI".
diff --git a/src/testdir/check.vim b/src/testdir/check.vim
index 4381c4e..f176f83 100644
--- a/src/testdir/check.vim
+++ b/src/testdir/check.vim
@@ -83,7 +83,7 @@
 command CheckCanRunGui call CheckCanRunGui()
 func CheckCanRunGui()
   if !has('gui') || ($DISPLAY == "" && !has('gui_running'))
-    throw 'Skipped: cannot run start the GUI'
+    throw 'Skipped: cannot start the GUI'
   endif
 endfunc