Bump actions/attest-build-provenance from 1.0.0 to 1.4.3 (#631)

Bumps [actions/attest-build-provenance](https://github.com/actions/attest-build-provenance) from 1.0.0 to 1.4.3.
- [Release notes](https://github.com/actions/attest-build-provenance/releases)
- [Changelog](https://github.com/actions/attest-build-provenance/blob/main/RELEASE.md)
- [Commits](actions/attest-build-provenance@897ed5e...1c608d1)

---
updated-dependencies:
- dependency-name: actions/attest-build-provenance
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build-docker-images.yml

@@ -95,7 +95,7 @@ jobs:
         run: docker push ghcr.io/pyca/${{ matrix.IMAGE.TAG_NAME }}
         if: (github.event_name == 'push' || github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main'
       - name: Generate attestation
-        uses: actions/attest-build-provenance@897ed5eab6ed058a474202017ada7f40bfa52940  # v1.0.0
+        uses: actions/attest-build-provenance@1c608d11d69870c2092266b3f9a6f3abbf17002c  # v1.4.3
         with:
           subject-name: "ghcr.io/pyca/${{ steps.image-digest.outputs.IMAGE_NAME }}"
           subject-digest: ${{ steps.image-digest.outputs.DIGEST }}