patch 9.0.0573: outdated dependencies go unnoticed

Problem:    Outdated dependencies go unnoticed.
Solution:   Use github Dependabot. (closes #11213)
diff --git a/src/version.c b/src/version.c
index b07c013..4428687 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    573,
+/**/
     572,
 /**/
     571,