Bump protobuf from 4.25.4 to 4.25.8 in /results-processor (#4440)

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 4.25.4 to 4.25.8.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v4.25.4...v4.25.8)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 4.25.8
  dependency-type: indirect
...

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

Author: dependabot[bot]

results-processor/requirements.txt

@@ -80,7 +80,7 @@ pathspec==0.12.1
     # via mypy
 proto-plus==1.22.3
     # via google-cloud-datastore
-protobuf==4.25.4
+protobuf==4.25.8
     # via
     #   google-api-core
     #   google-cloud-datastore