patch 8.2.3075: xxd always reports an old version string

Problem:    Xxd always reports an old version string. (Åsmund Ervik)
Solution:   Update the version string with the last known change date.
            (Jürgen Weigert, closes #8475)
diff --git a/src/testdir/test_xxd.vim b/src/testdir/test_xxd.vim
index 4eef7a4..922c5ab 100644
--- a/src/testdir/test_xxd.vim
+++ b/src/testdir/test_xxd.vim
@@ -226,7 +226,7 @@
 func Test_xxd_version()
   new
   exe 'r! ' . s:xxd_cmd . ' -v'
-  call assert_match("xxd V1.10 .* by Juergen Weigert", join(getline(1, 3)))
+  call assert_match('xxd 20\d\d-\d\d-\d\d by Juergen Weigert et al\.', join(getline(1, 3)))
   bwipe!
 endfunc