patch 8.2.0091: compiler warnings for size_t / int types

Problem:    Compiler warnings for size_t / int types.
Solution:   Change type to size_t. (Mike Williams)
diff --git a/src/version.c b/src/version.c
index 43300cb..d235ae7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    91,
+/**/
     90,
 /**/
     89,