Bump node-forge from 1.3.1 to 1.4.0 in /samples/spa-client

Bumps [node-forge](https://github.com/digitalbazaar/forge) from 1.3.1 to 1.4.0.
- [Changelog](https://github.com/digitalbazaar/forge/blob/main/CHANGELOG.md)
- [Commits](digitalbazaar/forge@v1.3.1...v1.4.0)

---
updated-dependencies:
- dependency-name: node-forge
  dependency-version: 1.4.0
  dependency-type: indirect
...

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

Author: dependabot[bot]