Create dep-maintainers for dependency updates

[haydentherapper]

Will be set as a codeowner for go.mod/sum updates in select repos and added to the push restrictions list for those repos

Summary

Release Note

Documentation

[haydentherapper]

Thanks @codysoyland for the idea!

This is to fix sigstore/cosign#3967, so that @cpanato can still approve and merge PRs while we can fix codeowner assignment.

[github-actions]

🍹 preview on sigstore-github-sync/sigstore/github-prod

Pulumi report

  Previewing update (sigstore/github-prod)

View Live: https://app.pulumi.com/sigstore/sigstore-github-sync/github-prod/previews/07ae2d5f-717f-4f3b-afc8-87601ceccd7a

@ Previewing update.....
pulumi:pulumi:Stack: (same)
  [urn=urn:pulumi:github-prod::sigstore-github-sync::pulumi:pulumi:Stack::sigstore-github-sync-github-prod]
  + github:index/team:Team: (create) 🔒
      [urn=urn:pulumi:github-prod::sigstore-github-sync::github:index/team:Team::dep-maintainers]
      [provider=urn:pulumi:github-prod::sigstore-github-sync::pulumi:providers:github::default_6_6_0::6b4fe4fa-33d1-454e-aea1-c3905d0b89f1]
      createDefaultMaintainer: false
      description            : "Team for maintainers across repos who manage dependency updates"
      name                   : "dep-maintainers"
      parentTeamId           : ""
      privacy                : "closed"
@ Previewing update....
Resources:
  + 1 to create
  568 unchanged