Bump protobuf from 4.25.3 to 5.26.0 in /external/price_server

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 4.25.3 to 5.26.0.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v4.25.3...v5.26.0)

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

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

external/price_server/requirements.txt

@@ -35,7 +35,7 @@ opentelemetry-semantic-conventions==0.44b0
 opentelemetry-util-http==0.44b0
 packaging==24.0
 platformdirs==4.2.0
-protobuf==4.25.3
+protobuf==5.26.0
 psycopg2==2.9.9
 pylint==3.1.0
 pynvim==0.5.0