patch 8.2.0421: interrupting with CTRL-C does not always work

Problem:    Interrupting with CTRL-C does not always work.
Solution:   Recognize CTRL-C while modifyOtherKeys is set.
diff --git a/src/version.c b/src/version.c
index 1ad99cf..986a29f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    421,
+/**/
     420,
 /**/
     419,