submodules: bump external/sapphire-paratime from a70b796 to d45181d

Bumps [external/sapphire-paratime](https://github.com/oasisprotocol/sapphire-paratime) from `a70b796` to `d45181d`.
- [Release notes](https://github.com/oasisprotocol/sapphire-paratime/releases)
- [Commits](oasisprotocol/sapphire-paratime@a70b796...d45181d)

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

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