submodules: bump external/oasis-core from cbd96df to 9f50f1a

Bumps [external/oasis-core](https://github.com/oasisprotocol/oasis-core) from `cbd96df` to `9f50f1a`.
- [Release notes](https://github.com/oasisprotocol/oasis-core/releases)
- [Commits](oasisprotocol/oasis-core@cbd96df...9f50f1a)

---
updated-dependencies:
- dependency-name: external/oasis-core
  dependency-version: 9f50f1a3a602a0f1cfa650a16ed6bc39569a0705
  dependency-type: direct:production
...

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

Author: dependabot[bot]