patch 9.0.0426: failed flaky tests reports only start time

Problem:    Failed flaky tests reports only start time.
Solution:   Also report the end time.

src/testdir/runtest.vim

@@ -479,7 +479,8 @@ for g:testfunc in sort(s:tests)
       call add(s:messages, 'Found errors in ' .. g:testfunc .. ':')
       call extend(s:messages, v:errors)
 
-      call add(total_errors, starttime .. ' Run ' .. g:run_nr .. ':')
+      let endtime = strftime("%H:%M:%S")
+      call add(total_errors, $'Run {g:run_nr}, {starttime} - {endtime}:')
       call extend(total_errors, v:errors)
 
       if g:run_nr >= 5 || prev_error == v:errors[0]

src/version.c

@@ -703,6 +703,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    426,
 /**/
     425,
 /**/