Fix go version in the hack/ensure-go.sh script (#875)

Co-authored-by: Manjunath A Kumatagi <[email protected]>

Author: k8s-infra-cherrypick-robot

hack/ensure-go.sh

@@ -31,7 +31,7 @@ EOF
   local go_version
   IFS=" " read -ra go_version <<< "$(go version)"
   local minimum_go_version
-  minimum_go_version=go1.16.0
+  minimum_go_version=go1.18.0
   if [[ "${minimum_go_version}" != $(echo -e "${minimum_go_version}\n${go_version[2]}" | sort -s -t. -k 1,1 -k 2,2n -k 3,3n | head -n1) && "${go_version[2]}" != "devel" ]]; then
     cat <<EOF
 Detected go version: ${go_version[*]}.