patch 8.2.0077: settagstack() cannot truncate at current index

Problem:    settagstack() cannot truncate at current index.
Solution:   Add the "t" action. (Yegappan Lakshmanan, closes #5417)
diff --git a/src/version.c b/src/version.c
index 263ffb0..118dad5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    77,
+/**/
     76,
 /**/
     75,