Revert "Fix formatting of CODEOWNERS"

[haydentherapper]

Reverts #3957

One of Sigstore's admins helps maintain a number of repos without explicitly being a codeowner. It seems like almost every repo across the Sigstore org has this same syntax error, which means effectively we haven't been using codeowners files for approvals. I have a few thoughts on ideas to fix this, but for now, I'm reverting this change so the admin can continue merging PRs.

A few ideas for fixes:

• Remove requiring codeowners approvals (each repo should be making that decision, and it's not ideal for the lack of notifications)
• Remove push restrictions (-1 on this, this mandates those with maintain can merge, but not those with write, which lets us implement review vs merge permissions)
• Allow admins to bypass branch protection rules (-1 on this, insider risk mitigation)

[codysoyland]

@haydentherapper Is this mostly for Dependabot updates? If so, we could add a "dep-maintainer" group (or even just Carlos's username) and give it ownership of go.mod/go.sum.

[haydentherapper]

Thanks @codysoyland for the suggestion, I've created PRs to create dep-maintainers and grant it maintainer perms over cosign, fulcio, rekor and sigstore/sigstore. Then we can fix the codeowners syntax and grant the team ownership over go.mod/sum