Update main.workflow with secrets

At the very least the login should succeed

.github/main.workflow

@@ -1,17 +1,21 @@
 workflow "New workflow" {
   on = "push"
-  resolves = ["./scripts/publish-manager.sh"]
+  resolves = ["push"]
 }
 
 action "Docker Registry" {
   uses = "actions/docker/login@86ff551d26008267bb89ac11198ba7f1d807b699"
+  secrets = ["DOCKER_USERNAME", "DOCKER_PASSWORD", "DOCKER_REGISTRY_URL"]
 }
 
-action "./scripts/publish-manager.sh" {
-  uses = "./scripts/publish-manager.sh"
+action "build" {
+  uses = "actions/docker/cli@master"
   needs = ["Docker Registry"]
-  env = {
-    TAG = "latest"
-    REGISTRY = "docker.pkg.github.com/kubernetes-sigs/cluster-api-provider-docker"
-  }
+  args = "build -t docker.pkg.github.com/kubernetes-sigs/cluster-api-provider-docker:latest ."
+}
+
+action "push" {
+  uses = "actions/docker/cli@master"
+  needs = ["build"]
+  args = "push docker.pkg.github.com/kubernetes-sigs/cluster-api-provider-docker:latest"
 }