patch 9.1.0437: Motif requires non-const char pointer for XPM  data

Problem:  Motif requires non-const char pointer for XPM data shared with
          GTK (Tony Mechelynck, after v9.1.0432)
Solution: Cast non-const to const char pointer for GTK (Drew Vogel).

closes: #14834

Signed-off-by: Drew Vogel <dvogel@github>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 98ec475..7188cbd 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    437,
+/**/
     436,
 /**/
     435,