Update release tools

[xing-yang]

Squashed 'release-tools/' changes from 5d874cc..c6a88c6

c6a88c6 Merge pull request #113 from xing-yang/install_snapshot_controller
45ec4c6 Fix the install of snapshot CRDs and controller

git-subtree-dir: release-tools
git-subtree-split: c6a88c6ed96b939bd150472b12693252942116c7

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

@xing-yang: The following test failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-kubernetes-csi-external-resizer-1-19-on-kubernetes-1-19	0b40f21	link	/test pull-kubernetes-csi-external-resizer-1-19-on-kubernetes-1-19

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[pohly]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pohly, xing-yang

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• release-tools/OWNERS [pohly]

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[pohly]

/retest