runtime(vim): update Vim Syntax generator

- Add missing "Last Change:" line.
- The date on this line in vim.vim is updated by update_date.vim at
  Make time. (I made a mistake in the file path)
- Remove unnecessary "b:loaded_syntax_vim_ex".
- Remove "Base File Date:" line in vim.vim.base
- Add Doug Kearns as Maintainer

closes: #14031

Signed-off-by: h-east <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/generator/vim.vim.base

@@ -1,11 +1,12 @@
 " Vim syntax file
 " Language:	Vim script
 " Maintainer:	Hirohito Higashi <h.east.727 ATMARK gmail.com>
+" 	Doug Kearns <dougkearns@gmail.com>
 " URL:	https://github.com/vim-jp/syntax-vim-ex
+" Last Change:	Feb 13, 2024
 " Former Maintainer: Charles E. Campbell <NcampObell@SdrPchip.AorgM-NOSPAM>
 " Base File URL:     http://www.drchip.org/astronaut/vim/index.html#SYNTAX_VIM
 " Base File Version: 9.0-25
-" Base File Date:    May 09, 2023
 
 " DO NOT CHANGE DIRECTLY.
 " THIS FILE PARTLY GENERATED BY gen_syntax_vim.vim.
@@ -17,7 +18,6 @@
 if exists("b:current_syntax")
   finish
 endif
-let b:loaded_syntax_vim_ex="__REVISION__"
 let s:keepcpo= &cpo
 set cpo&vim