patch 8.2.0891: clang warns for invalid conversion

Problem:    Clang warns for invalid conversion.
Solution:   Use zero instead of INVALCOLOR.
diff --git a/src/version.c b/src/version.c
index 986df70..b0fd4b3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    891,
+/**/
     890,
 /**/
     889,