chore: update blunderbuss.yml (#1484)

Co-authored-by: Chandrashekhar Sirimala <chandrasiri@google.com>

Author: cojenco

.github/blunderbuss.yml

@@ -4,7 +4,7 @@
 # Note: This file is autogenerated. To make changes to the assignee
 # team, please update `codeowner_team` in `.repo-metadata.json`.
 assign_issues:
-  - cojenco
+  - chandra-siri
 
 assign_prs:
-  - cojenco
+  - chandra-siri