Bump ws from 6.2.1 to 6.2.2 in /ploneconf2020-grace_under_fire

Bumps [ws](https://github.com/websockets/ws) from 6.2.1 to 6.2.2.
- [Release notes](https://github.com/websockets/ws/releases)
- [Commits](https://github.com/websockets/ws/commits)

---
updated-dependencies:
- dependency-name: ws
  dependency-type: indirect
...

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

Author: dependabot[bot]