drop Gopkg.toml from publishing bot rules

[BenTheElder]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Removes Gopkg.toml delete rule, we haven't had a Gopkg.toml for ages, and dep isn't widely in use anymore, the repository is a read-only public archive deprecated in 2020 https://github.com/golang/dep.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

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[nikhita]

/lgtm
/approve

Thanks for cleaning this up!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: BenTheElder, nikhita

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• staging/publishing/OWNERS [nikhita]

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