Disable cosign verification by default (#199)

Since we can't sign the current builder, we also need to disable
verification of it's signature. This avoids another chicken-egg-problem.

action.yml

@@ -25,10 +25,6 @@ runs:
     - shell: bash
       run: |
         docker pull ghcr.io/home-assistant/amd64-builder:${{ steps.version.outputs.version }}
-        cosign verify \
-          --certificate-oidc-issuer https://token.actions.githubusercontent.com \
-          --certificate-identity-regexp https://github.com/home-assistant/builder/.* \
-          ghcr.io/home-assistant/amd64-builder:${{ steps.version.outputs.version }}
 
     - shell: bash
       id: builder