Bump @sigstore/protobuf-specs from 0.1.0 to 0.2.1 (#888)

Bumps [@sigstore/protobuf-specs](https://github.com/sigstore/protobuf-specs) from 0.1.0 to 0.2.1.
- [Release notes](https://github.com/sigstore/protobuf-specs/releases)
- [Changelog](https://github.com/sigstore/protobuf-specs/blob/main/CHANGELOG.md)
- [Commits](sigstore/protobuf-specs@v0.1.0...v0.2.1)

---
updated-dependencies:
- dependency-name: "@sigstore/protobuf-specs"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

packages/verify/package.json

@@ -26,7 +26,7 @@
     "provenance": true
   },
   "dependencies": {
-    "@sigstore/protobuf-specs": "^0.1.0",
+    "@sigstore/protobuf-specs": "^0.2.1",
     "@sigstore/bundle": "^2.1.0",
     "@sigstore/core": "^0.1.0"
   },