vim-patch:9.2.0562: filetype: SGF files are not recognized

Problem:  filetype: SGF files are not recognized
Solution: Detect *.sgf as sgf filetype
          (Borys Lykah)

Reference:
https://www.red-bean.com/sgf/index.html

closes: vim/vim#20349

dda45ba88f

Co-authored-by: Borys Lykah <lykahb@fastmail.com>

runtime/lua/vim/filetype.lua

@@ -1191,6 +1191,7 @@ local extension = {
   sdl = 'sdl',
   sed = 'sed',
   sexp = 'sexplib',
+  sgf = 'sgf',
   bash = detect.bash,
   bats = detect.bash,
   cygport = detect.bash,