Proposal: 🏃golang: update go to 1.13.7

Dockerfile

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 # Build the manager binary
-FROM golang:1.12.9 as builder
+FROM golang:1.13.7 as builder
 WORKDIR /workspace
 
 # Run this with docker build --build_arg $(go env GOPROXY) to override the goproxy

go.mod

@@ -1,6 +1,6 @@
 module sigs.k8s.io/cluster-api-provider-openstack
 
-go 1.12
+go 1.13
 
 require (
 	github.com/go-logr/logr v0.1.0

hack/ensure-go.sh

@@ -31,7 +31,7 @@ EOF
   local go_version
   IFS=" " read -ra go_version <<< "$(go version)"
   local minimum_go_version
-  minimum_go_version=go1.12.1
+  minimum_go_version=go1.13.0
   if [[ "${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[*]}.

hack/tools/go.mod

@@ -1,14 +1,10 @@
 module sigs.k8s.io/cluster-api/hack/tools
 
-go 1.12
+go 1.13
 
 require (
 	github.com/golang/mock v1.3.1
-	github.com/golangci/go-tools v0.0.0-20180109140146-af6baa5dc196 // indirect
 	github.com/golangci/golangci-lint v1.19.1
-	github.com/golangci/gosec v0.0.0-20180901114220-66fb7fc33547 // indirect
-	gopkg.in/airbrake/gobrake.v2 v2.0.9 // indirect
-	gopkg.in/gemnasium/logrus-airbrake-hook.v2 v2.1.2 // indirect
 	sigs.k8s.io/controller-tools v0.2.0
 	sigs.k8s.io/kustomize/kustomize/v3 v3.4.0
 	sigs.k8s.io/testing_frameworks v0.1.1