fix: add subject-name to attest-build-provenance step (#51)

The actions/attest-build-provenance action requires subject-name when
subject-digest is provided. Added the OCI ref (ghcr.io/jorisjonkers-dev/
<artifact-name>:deploy-<version>) as the subject name, matching the tag
scheme used in publish.sh.

Co-authored-by: JorisJonkers Agent <agents@jorisjonkers.dev>

Author: jorisjonkers-dev-agents[bot]

.github/workflows/deploy-artifact.yml

@@ -133,6 +133,7 @@ jobs:
         if: ${{ steps.publish.outputs.artifact-digest != '' }}
         uses: actions/attest-build-provenance@c074443f1aee8d4aeeae555aebba3282517141b2 # v2.2.3
         with:
+          subject-name: ghcr.io/jorisjonkers-dev/${{ inputs.artifact-name }}:deploy-${{ inputs.artifact-version }}
           subject-digest: ${{ steps.publish.outputs.artifact-digest }}
           push-to-registry: true