Bump required go version to 1.13

[rhafer]

Recent versions of libpod use features from github.com/pkg/errors
that are only available when building with go 1.13 or newer.

[openshift-ci-robot]

Hi @rhafer. Thanks for your PR.

I'm waiting for a containers 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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[vrothberg]

LGTM, thanks for the fix!

[rhatdan]

/lgtm
/approve
/hold

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rhafer, rhatdan

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[mheon]

/hold cancel