Request: Update the CODEOWNERS.md with the current list of maintainers

[TheFoxAtWork]

Description

In trying to assess the current activity and support of the cosign project, it appears the CODEOWNERS.md file may be out of date. As i understand it, this doesn't truly reflect the maintainers but is used to by GitHub to trigger reviews, if its not identifying the right individuals, this could lead to delays in having PRs reviewed.

Specifically - it appears this individual is performing much of the work and looks to be an "active" maintainer but isn't listed as such.

Also given the criticality of the cosign project to the Sigstore ecosystem the health and maintenance of this project seems paramount.

(i recognize that in pointing this out i am inevitably creating additional work for the project which may not have a many maintainers but I hope this is something under consideration by the Sigstore TSC for the core elements of the Sigstore project).