patch 8.2.0978: leaking memory in termcodes test

Problem:    Leaking memory in termcodes test.
Solution:   Set t_8u with set_option_value().
diff --git a/src/version.c b/src/version.c
index f2170ef..2c2c573 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    978,
+/**/
     977,
 /**/
     976,