chore(deps-dev): bump elliptic from 6.5.4 to 6.6.1 in /demo

Bumps [elliptic](https://github.com/indutny/elliptic) from 6.5.4 to 6.6.1.
- [Commits](indutny/elliptic@v6.5.4...v6.6.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]