Upgrading Bikeshed in spec-prod action

Hi all,

I've sent https://github.com/w3c/spec-prod/pull/223 to upgrade Bikeshed to
v7 in the spec-prod Github action. It's been pinned to v5 since December
<https://github.com/w3c/spec-prod/pull/219>. If you know that your spec
doesn't work with v7, please file Bikeshed bugs
<https://github.com/speced/bikeshed/issues>, but you can pin your action
to v2.12.2 if they're not fixed before the next spec-prod release.

Jeffrey