patch 8.1.0546: modeline test with keymap fails

Problem:    Modeline test with keymap fails.
Solution:   Check that the keymap feature is available.
diff --git a/src/version.c b/src/version.c
index 42ce472..ce8595e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    546,
+/**/
     545,
 /**/
     544,