Update nightly-release.yml [skip ci]

Author: UnschooledGamer

.github/workflows/nightly-release.yml

@@ -140,6 +140,6 @@ jobs:
     uses: slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@v2.1.0
     with:
        # base64 of lines in sha256sum format: "<sha256><two spaces><path-or-name>"
-     base64-subjects: "${{ needs.release.outputs.hashes_b64 }}"
+     base64-subjects-as-file: "${{ needs.release.outputs.subjects_file }}"
      upload-assets: true
      upload-tag-name: "${{ needs.release.outputs.nightly_tag_name }}"