Merge pull request #399 from davidz627/fix/stale

Clean up stale testgrids from README

Author: k8s-ci-robot

README.md

@@ -22,9 +22,7 @@ Latest stable image: `gcr.io/gke-release/gcp-compute-persistent-disk-csi-driver:
 |----------------|--------------------|-------------|
 | HEAD Latest | HEAD | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Kubernetes%20Master%20Driver%20Latest/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Kubernetes%20Master%20Driver%20Latest) |
 | 0.5.x Stable | HEAD | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Kubernetes%20Master%20Driver%20Release%200.5/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Kubernetes%20Master%20Driver%20Release%200.5) |
-| 0.4.x Stable | HEAD | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Kubernetes%20Master%20Driver%20Release%200.4/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Kubernetes%20Master%20Driver%20Release%200.4) |
 | 0.4.x Stable | 1.13.5 | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Kubernetes%20v1.13.5%20Driver%20Release%200.4/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Kubernetes%20v1.13.5%20Driver%20Release%200.4) |
-| 0.3.x Stable | HEAD | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Kubernetes%20Master%20Driver%20Release%200.3/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Kubernetes%20Master%20Driver%20Release%200.3) |
 | HEAD Latest | HEAD (Migration ON) | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Migration%20Kubernetes%20Master%20Driver%20Latest/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Migration%20Kubernetes%20Master%20Driver%20Latest) |
 | HEAD Stable | HEAD (Migration ON) | [<img alt="Test Status" src="https://testgrid.k8s.io/q/summary/provider-gcp-compute-persistent-disk-csi-driver/Migration%20Kubernetes%20Master%20Driver%20Stable/tests_status" />](https://testgrid.k8s.io/provider-gcp-compute-persistent-disk-csi-driver#Migration%20Kubernetes%20Master%20Driver%20Stable) |