scripts,tests: Bump kubernetes version to 1.18

scripts/minikube-start.sh

@@ -2,7 +2,7 @@
 minikube delete
 minikube addons disable metrics-server
 minikube start \
-    --kubernetes-version=v1.16.0 \
+    --kubernetes-version=v1.18.1 \
     --memory=6g \
     --bootstrapper=kubeadm \
     --extra-config=kubelet.authentication-token-webhook=true \

tests/e2e/travis-e2e.sh

@@ -13,7 +13,7 @@ chmod +x kubectl
 curl -Lo kind https://github.com/kubernetes-sigs/kind/releases/download/v0.6.1/kind-linux-amd64
 chmod +x kind
 
-./kind create cluster --image=kindest/node:v1.17.0
+./kind create cluster --image=kindest/node:v1.18.0
 export KUBECONFIG="$(./kind get kubeconfig-path)"
 
 # create namespace, permissions, and CRDs