Bumps [deps/protobuf](https://github.com/google/protobuf) from `15add1a` to `c756e61`.
- [Release notes](https://github.com/google/protobuf/releases)
- [Commits](15add1af49...c756e61878
)
---
updated-dependencies:
- dependency-name: deps/protobuf
dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <support@github.com>