vim-patch:9.0.1475: busted configuration files are not recognized (#23266)

Problem:    Busted configuration files are not recognized.
Solution:   Recognize busted configuration files as Lua. (Craig MacEachern,
            closes vim/vim#12209)

Co-authored-by: C.D. MacEachern <craig.daniel.maceachern@gmail.com>

runtime/lua/vim/filetype.lua

@@ -1522,6 +1522,7 @@ local filename = {
   ['.lsl'] = function(path, bufnr)
     return require('vim.filetype.detect').lsl(bufnr)
   end,
+  ['.busted'] = 'lua',
   ['.luacheckrc'] = 'lua',
   ['lynx.cfg'] = 'lynx',
   ['m3overrides'] = 'm3build',