patch 9.0.1318: code style test fails

Problem:    Code style test fails.
Solution:   Remove trailing white space.
diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index f1aadde..e73b31c 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -190,7 +190,7 @@
         this.value = 'xyz'
       endclass
 
-      var state: State 
+      var state: State
       var db = {'xyz': 789}
       echo db[state.value]
   END