patch 9.0.1853: CI error on different signedness in regexp.c

Problem:  CI error on different signedness in regexp.c
          (after patch 9.0.1848)
Solution: Cast strlen() call to int

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1853,
 /**/
     1852,
 /**/