fix errors in cloudbuild.yaml

Author: ComradeProgrammer

hack/prow/image/kubernetes-bootcamp/cloudbuild.yaml

@@ -2,15 +2,15 @@
 options:
   substitution_option: ALLOW_LOOSE
 steps:
-- name: gcr.io/k8s-staging-test-infra/gcb-docker-gcloud:v20250513-9264efb079
-  entrypoint: make
-  env:
-    - DOCKER_CLI_EXPERIMENTAL=enabled
-    - _GIT_TAG=$_GIT_TAG
-    - _PULL_BASE_REF=$_PULL_BASE_REF
-  args:
-    - push-kubernetes-bootcamp
-  substitutions:
+  - name: gcr.io/k8s-staging-test-infra/gcb-docker-gcloud:v20250513-9264efb079
+    entrypoint: make
+    env:
+      - DOCKER_CLI_EXPERIMENTAL=enabled
+      - _GIT_TAG=$_GIT_TAG
+      - _PULL_BASE_REF=$_PULL_BASE_REF
+    args:
+      - push-kubernetes-bootcamp
+substitutions:
   # _GIT_TAG will be filled with a git-based tag for the image, of the form vYYYYMMDD-hash, and
   # can be used as a substitution
   _GIT_TAG: '12345'