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] <[email protected]>

.github/workflows/build.yml

@@ -24,7 +24,7 @@ jobs:
       - run: just build
 
       - name: Attest Build Provenance
-        uses: actions/attest-build-provenance@v1
+        uses: actions/attest-build-provenance@v2
         with:
           subject-path: dist/anycastd-*
 
@@ -76,7 +76,7 @@ jobs:
           platforms: linux/amd64,linux/arm/v7,linux/arm64
 
       - name: Attest Build Provenance
-        uses: actions/attest-build-provenance@v1
+        uses: actions/attest-build-provenance@v2
         with:
           subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}
           subject-digest: ${{ steps.push.outputs.digest }}