Bump protobuf in /examples/trace-analytics-sample-app/sample-app

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.20.3 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@v3.20.3...v4.25.8)

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

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

Author: dependabot[bot]

examples/trace-analytics-sample-app/sample-app/requirements.txt

@@ -5,7 +5,7 @@ opentelemetry-instrumentation-flask==0.46b0
 opentelemetry-instrumentation-mysql==0.46b0
 opentelemetry-instrumentation-requests==0.46b0
 opentelemetry-sdk==1.25.0
-protobuf==3.20.3
+protobuf==4.25.8
 requests==2.32.0
 setuptools==70.0.0
 urllib3==2.5.0