build(deps): Bump protobuf from 5.27.3 to 5.28.1 in /requirements

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 5.27.3 to 5.28.1.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v5.27.3...v5.28.1)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements/requirements.txt

@@ -6,7 +6,7 @@ ifaddr==0.2.0
 ifaddr==0.2.0
 mediafile==0.12.0
 miniaudio==1.61
-protobuf==5.27.3
+protobuf==5.28.1
 pydantic==2.8.2
 requests==2.32.3
 srptools==1.0.1