patch 9.1.0522: Vim9: string(object) hangs for recursive references

Problem:  Vim9: string(object) hangs for recursive references
Solution: Handle recursive objects specifically, add a hang test and a
          compare test (Ernie Rael)

fixes: #15080
closes: #15082

Signed-off-by: Ernie Rael <errael@raelity.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 7e4b647..249d1c5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    522,
+/**/
     521,
 /**/
     520,