Merge pull request #1415 from fluxcd/label-1.5

Add backport:release/v1.5.x label

Author: matheuscscp

.github/labels.yaml

@@ -28,3 +28,6 @@
 - name: backport:release/v1.4.x
   description: To be backported to release/v1.4.x
   color: '#ffd700'
+- name: backport:release/v1.5.x
+  description: To be backported to release/v1.5.x
+  color: '#ffd700'