vim-patch:9.0.1438: .fs files are falsely recognized as forth files (#22871)

Problem:    .fs files are falsely recognized as forth files.
Solution:   Check 100 lines for something that looks like forth. (Johan
            Kotlinski, closes vim/vim#12219, closes vim/vim#11988)

065088d554

Co-authored-by: Johan Kotlinski <kotlinski@gmail.com>

runtime/lua/vim/filetype/detect.lua

@@ -473,12 +473,12 @@ function M.fs(bufnr)
   if vim.g.filetype_fs then
     return vim.g.filetype_fs
   end
-  local line = nextnonblank(bufnr, 1)
-  if findany(line, { '^%s*%.?%( ', '^%s*\\G? ', '^\\$', '^%s*: %S' }) then
-    return 'forth'
-  else
-    return 'fsharp'
+  for _, line in ipairs(getlines(bufnr, 1, 100)) do
+    if line:find('^[:(\\] ') then
+      return 'forth'
+    end
   end
+  return 'fsharp'
 end
 
 function M.git(bufnr)