vim-patch:9.0.1348: Un-grammar files are not recognized (#22383)

Problem:    Un-grammar files are not recognized.
Solution:   Add patterns for Un-grammar files. (Amaan Qureshi, closes vim/vim#12034)

44e08c1cf8

src/nvim/testdir/test_filetype.vim

@@ -609,6 +609,7 @@ let s:filename_checks = {
     \ 'typescript': ['file.mts', 'file.cts'],
     \ 'typescript.glimmer': ['file.gts'],
     \ 'typescriptreact': ['file.tsx'],
+    \ 'ungrammar': ['file.ungram'],
     \ 'uc': ['file.uc'],
     \ 'udevconf': ['/etc/udev/udev.conf', 'any/etc/udev/udev.conf'],
     \ 'udevperm': ['/etc/udev/permissions.d/file.permissions', 'any/etc/udev/permissions.d/file.permissions'],