patch 8.1.0637: nsis file no longer used

Problem:    Nsis file no longer used.
Solution:   Remove the file. (Ken Takata)
diff --git a/src/version.c b/src/version.c
index b2dbe38..c51a46d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    637,
+/**/
     636,
 /**/
     635,