patch 8.2.3481: failures when char is unsigned

Problem:    Failures when char is unsigned.
Solution:   Use int8_T.  Make a CI run with unsigned char. (James McCoy,
            closes #8936)
diff --git a/src/version.c b/src/version.c
index 70f363a..31fb2a6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3481,
+/**/
     3480,
 /**/
     3479,