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>
diff --git a/src/version.c b/src/version.c
index 61fe83b..fe1495a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1853,
+/**/
     1852,
 /**/
     1851,