submodules: bump external/sapphire-paratime from 68206d9 to a4069ee

Bumps [external/sapphire-paratime](https://github.com/oasisprotocol/sapphire-paratime) from `68206d9` to `a4069ee`.
- [Release notes](https://github.com/oasisprotocol/sapphire-paratime/releases)
- [Commits](oasisprotocol/sapphire-paratime@68206d9...a4069ee)

---
updated-dependencies:
- dependency-name: external/sapphire-paratime
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>