fix: authenticate registry before image attestation (#162)

Author: mldangelo-oai

.github/workflows/container-release.yml

@@ -530,6 +530,13 @@ jobs:
       packages: write
 
     steps:
+      - name: Sign in to GitHub Container Registry
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Sign verified multiarchitecture candidate provenance
         uses: actions/attest-build-provenance@96b4a1ef7235a096b17240c259729fdd70c83d45 # v2
         with: