Merge pull request #5255 from cpanato/add-capg-channel

slack: add cluster-api-gcp channel

Author: k8s-ci-robot

communication/slack-config/channels.yaml

@@ -44,6 +44,7 @@ channels:
   - name: cluster-api-digitalocean
   - name: cluster-api-docker
     archived: true
+  - name: cluster-api-gcp
   - name: cluster-api-nested
   - name: cluster-api-openstack
   - name: cluster-api-packet