Bump actions/attest-build-provenance from 1 to 2

Bumps [actions/attest-build-provenance](https://github.com/actions/attest-build-provenance) from 1 to 2.
- [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@v1...v2)

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

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

.github/workflows/build-ffmpeg.yaml

@@ -136,7 +136,7 @@ jobs:
           
       - name: Generate artifact attestation for FFmpeg binaries
         if: '! inputs.no_release'
-        uses: actions/attest-build-provenance@v1
+        uses: actions/attest-build-provenance@v2
         with:
           subject-path: ff*.exe
 
@@ -145,7 +145,7 @@ jobs:
 
       - name: Generate artifact attestation for FFmpeg archive
         if: '! inputs.no_release'
-        uses: actions/attest-build-provenance@v1
+        uses: actions/attest-build-provenance@v2
         with:
           subject-path: ffmpeg-${{ needs.check.outputs.version }}-${{ needs.check.outputs.helper-git-sha-short }}-${{ matrix.os }}-nonfree.7z