Bump machine controller image

[kcoronado]

What this PR does / why we need it:
This PR bumps the GCE machine controller tag after pushing the new machine controller image due to changes in #107. This image contains changes up to and including commit ec53b5b

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Release note:

@kubernetes/kube-deploy-reviewers

[kcoronado]

/assign @krousey @jessicaochen

[k8s-ci-robot]

Hi @kcoronado. Thanks for your PR.

I'm waiting for a kubernetes or kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[krousey]

/ok-to-test
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kcoronado, krousey

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