update to Go 1.12.4

[pohly]

No description provided.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pohly

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[pohly]

/test pull-kubernetes-csi-csi-driver-host-path-1-13-on-kubernetes-1-13
/test pull-kubernetes-csi-csi-driver-host-path-1-13-on-kubernetes-master
/test pull-kubernetes-csi-csi-driver-host-path-1-14-on-kubernetes-1-14
/test pull-kubernetes-csi-csi-driver-host-path-1-14-on-kubernetes-master
/test pull-kubernetes-csi-csi-driver-host-path-alpha-1-13-on-kubernetes-1-13
/test pull-kubernetes-csi-csi-driver-host-path-alpha-1-14-on-kubernetes-1-14
/test pull-kubernetes-csi-csi-driver-host-path-unit

[msau42]

/lgtm
/hold
until we after we release a new hostpath driver

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle stale

[pohly]

Was merged via #76