Update hub version

Signed-off-by: divyansh42 <[email protected]>

Author: divyansh42

config/konflux/repos/tektoncd-hub.yaml

@@ -9,6 +9,6 @@ components:
 branches:
   # - name: main
   - name: release-v1.21.x
-    upstream: release-v1.23.5
+    upstream: release-v1.23.6
     versions:
       - "1.21"