vim-patch:9.0.1645: zserio files are not recognized (#24120)

Problem:    zserio files are not recognized.
Solution:   Add a pattern for zserio files. (Dominique Pellé,
            closes vim/vim#12544)

2b994da57a

Co-authored-by: =?UTF-8?q?Dominique=20Pell=C3=A9?= <dominique.pelle@gmail.com>

runtime/lua/vim/filetype.lua

@@ -1174,6 +1174,7 @@ local extension = {
   zir = 'zir',
   zu = 'zimbu',
   zut = 'zimbutempl',
+  zs = 'zserio',
   zsh = 'zsh',
   vala = 'vala',
   web = function(path, bufnr)