patch 9.0.1421: Nu files are not recognized

Problem:    Nu files are not recognized.
Solution:   Add a pattern for Nu files. (Amaan Qureshi, closes #12172)

Author: amaanq

runtime/filetype.vim

@@ -1399,6 +1399,9 @@ au BufNewFile,BufRead *.nse			setf lua
 " NSIS
 au BufNewFile,BufRead *.nsi,*.nsh		setf nsis
 
+" Nu
+au BufNewFile,BufRead {env,config}.nu		setf nu
+
 " Oblivion Language and Oblivion Script Extender
 au BufNewFile,BufRead *.obl,*.obse,*.oblivion,*.obscript  setf obse
 

src/testdir/test_filetype.vim

@@ -412,6 +412,7 @@ let s:filename_checks = {
     \ 'nqc': ['file.nqc'],
     \ 'nroff': ['file.tr', 'file.nr', 'file.roff', 'file.tmac', 'file.mom', 'tmac.file'],
     \ 'nsis': ['file.nsi', 'file.nsh'],
+    \ 'nu': ['env.nu', 'config.nu'],
     \ 'obj': ['file.obj'],
     \ 'obse': ['file.obl', 'file.obse', 'file.oblivion', 'file.obscript'],
     \ 'ocaml': ['file.ml', 'file.mli', 'file.mll', 'file.mly', '.ocamlinit', 'file.mlt', 'file.mlp', 'file.mlip', 'file.mli.cppo', 'file.ml.cppo'],

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1421,
 /**/
     1420,
 /**/