Merge pull request #1331 from fluxcd/label-1.9

Add backport:release/v1.9.x label

Author: matheuscscp

.github/labels.yaml

@@ -34,3 +34,6 @@
 - name: backport:release/v1.8.x
   description: To be backported to release/v1.8.x
   color: '#ffd700'
+- name: backport:release/v1.9.x
+  description: To be backported to release/v1.9.x
+  color: '#ffd700'