Bump protobuf in /contract-tests/images/mock-collector

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 4.25.2 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@v4.25.2...v4.25.8)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 4.25.8
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

contract-tests/images/mock-collector/pyproject.toml

@@ -13,7 +13,7 @@ dependencies = [
     "grpcio ~= 1.66.0",
     "opentelemetry-proto==1.25.0",
     "opentelemetry-sdk==1.25.0",
-    "protobuf==4.25.2",
+    "protobuf==4.25.8",
     "typing-extensions==4.12.2"
 ]
 

contract-tests/images/mock-collector/requirements.txt

@@ -1,5 +1,5 @@
 grpcio==1.66.2
 opentelemetry-proto==1.25.0
 opentelemetry-sdk==1.25.0
-protobuf==4.25.2
+protobuf==4.25.8
 typing-extensions==4.12.2