Bump psy/psysh from 0.11.18 to 0.11.20

Bumps [psy/psysh](https://github.com/bobthecow/psysh) from 0.11.18 to 0.11.20.
- [Release notes](https://github.com/bobthecow/psysh/releases)
- [Commits](bobthecow/psysh@v0.11.18...v0.11.20)

---
updated-dependencies:
- dependency-name: psy/psysh
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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