submodules: bump external/sapphire-paratime from 398f116 to 1f7939f

Bumps [external/sapphire-paratime](https://github.com/oasisprotocol/sapphire-paratime) from `398f116` to `1f7939f`.
- [Release notes](https://github.com/oasisprotocol/sapphire-paratime/releases)
- [Commits](oasisprotocol/sapphire-paratime@398f116...1f7939f)

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

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