patch 8.1.0325: strings in swap file may not be NUL terminated

Problem:    Strings in swap file may not be NUL terminated. (Coverity)
Solution:   Limit the length of the used string.
diff --git a/src/version.c b/src/version.c
index bf40df7..dfb0965 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    325,
+/**/
     324,
 /**/
     323,