fix: set signing key

Author: PierreJeanjacquot

.github/workflows/sconify.yml

@@ -110,10 +110,11 @@ jobs:
       - name: Sconify Image Prod
         if: ${{ !inputs.debug-only }}
         run: |
-          mkdir -p /sig && echo ${{ secrets.scone-signing-key }} > /sig/enclave-key.pem
+          mkdir -p $HOME/sig && echo ${{ secrets.scone-signing-key }} > $HOME/sig/enclave-key.pem
           docker run \
           --rm \
           -v /var/run/docker.sock:/var/run/docker.sock \
+          -v $HOME/sig/enclave-key.pem:/sig/enclave-key.pem
           registry.scontain.com/scone-production/iexec-sconify-image:${{ inputs.sconify-version }} \
           sconify_iexec \
           --from=${{ inputs.docker-registry }}/${{ inputs.image-name }}:${{ inputs.image-tag }} \