Don't sign images as it spams the registry

Signed-off-by: yubiuser <[email protected]>

Author: yubiuser

.github/workflows/ftl-build.yml

@@ -97,6 +97,8 @@ jobs:
             type=ref,event=tag
       meta-flavor: |
         latest=${{ startsWith(github.ref, 'refs/tags/') }}
+      # FIXME: GHCR does not support the referrers API and spams the registry with sha-tagged images when cosigned: https://github.com/docker/github-builder/issues/109
+      sign: false
     secrets:
       registry-auths: |
         - registry: docker.io