release-3.0: Update release tools

[ggriffiths]

What type of PR is this?
/kind cleanup

What this PR does / why we need it:
Updates this branch to latest rel tools

Which issue(s) this PR fixes:
n/a

Special notes for your reviewer:
n/a

Does this PR introduce a user-facing change?:

NONE

[ggriffiths]

/assign @xing-yang

[ggriffiths]

Includes all changes from release-tools master up until commit 5d874cc.

The latest release tools were failing on this branch: https://prow.k8s.io/view/gs/kubernetes-jenkins/pr-logs/pull/kubernetes-csi_external-snapshotter/436/pull-kubernetes-csi-external-snapshotter-1-19-on-kubernetes-1-19/1334383791833092096

[pohly]

The latest release tools were failing on this branch

This needs to be fixed. We can't be stuck on a non-recent csi-release-tools.

[xing-yang]

@ggriffiths we need to squash the commits. Can you try this script: kubernetes-csi/csi-release-tools#7 (comment)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[ggriffiths]

Ok, I've reopened a new PR with the script - had issues pushing directly to this branch and it was closed.
#437

[k8s-ci-robot]

@ggriffiths: The following tests failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-kubernetes-csi-external-snapshotter-1-17-on-kubernetes-1-17	271a825	link	/test pull-kubernetes-csi-external-snapshotter-1-17-on-kubernetes-1-17
pull-kubernetes-csi-external-snapshotter-1-19-on-kubernetes-1-19	271a825	link	/test pull-kubernetes-csi-external-snapshotter-1-19-on-kubernetes-1-19
pull-kubernetes-csi-external-snapshotter-1-18-on-kubernetes-1-18	271a825	link	/test pull-kubernetes-csi-external-snapshotter-1-18-on-kubernetes-1-18

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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