Disable cosign signature verification (#197)

The current version of cosign deployed in the latest builder doesn't
work with the currently deployed TUF Trust Root on the sigstore servers
(see also https://blog.sigstore.dev/tuf-root-update/).

Remove the cosign identity information to temporarily disable signature
verification. This allows to build a new release with a newer cosign.

build.yaml

@@ -5,9 +5,6 @@ build_from:
   armhf: "ghcr.io/home-assistant/armhf-base:3.18"
   amd64: "ghcr.io/home-assistant/amd64-base:3.18"
   i386: "ghcr.io/home-assistant/i386-base:3.18"
-cosign:
-  base_identity: https://github.com/home-assistant/docker-base/.*
-  identity: https://github.com/home-assistant/builder/.*
 args:
   YQ_VERSION: "v4.13.2"
   COSIGN_VERSION: "2.2.3"