patch 9.0.1281: Cadence files are not recognized

Problem:    Cadence files are not recognized.
Solution:   Recognize Cadence files. (Janez Podhostnik, closes #11951)
diff --git a/src/version.c b/src/version.c
index cdca151..d185852 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1281,
+/**/
     1280,
 /**/
     1279,