updated git fetch args to enable GCB fetch tags

Author: droot

build/cloudbuild.yaml

@@ -21,6 +21,8 @@
 # Release tar will be in $OUTPUT
 
 steps:
+- name: "gcr.io/cloud-builders/git"
+  args: [fetch, --depth=100]
 - name: "ubuntu"
   args: ["mkdir", "-p", "/workspace/_output/linux_amd64"]
 - name: "gcr.io/kubebuilder/thirdparty-linux:1.9"