build(deps): bump actions/attest-build-provenance from 3 to 4

Bumps [actions/attest-build-provenance](https://github.com/actions/attest-build-provenance) from 3 to 4.
- [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@v3...v4)

---
updated-dependencies:
- dependency-name: actions/attest-build-provenance
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -69,7 +69,7 @@ jobs:
           overwrite: true
 
       - name: Attest Artifact
-        uses: actions/attest-build-provenance@v3
+        uses: actions/attest-build-provenance@v4
         with:
           subject-name: mpv-macos-26-arm64.zip
           subject-digest: sha256:${{ steps.upload.outputs.artifact-digest }}