patch 9.2.0391: tests: Comment in test_vim9_cmd breaks syntax highlighting

Problem:  tests: Comment in test_vim9_cmd breaks syntax highlighting
Solution: Move the comment into the function and use the # as comment
          marker instead

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_vim9_cmd.vim

@@ -2103,8 +2103,8 @@ def s:check_previewpopup(expected_title: string)
   set previewpopup&
 enddef
 
-" Test for the 'previewpopup' option
 def Test_previewpopup()
+  # Test for the 'previewpopup' option
   CheckFeature quickfix
   set previewpopup=height:10,width:60
   pedit Xppfile

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    391,
 /**/
     390,
 /**/