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)
diff --git a/src/version.c b/src/version.c
index 32c39be..f6cac46 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1421,
+/**/
     1420,
 /**/
     1419,