vim-patch:9.0.1415: Crystal files are not recognized

Problem:    Crystal files are not recognized.
Solution:   Add a pattern for Crystal files. (Amaan Qureshi, closes vim/vim#12175)

7c4516fe93

Co-authored-by: Amaan Qureshi <amaanq12@gmail.com>

runtime/lua/vim/filetype.lua

@@ -265,6 +265,7 @@ local extension = {
   end,
   cql = 'cqlang',
   crm = 'crm',
+  cr = 'crystal',
   csx = 'cs',
   cs = 'cs',
   csc = 'csc',