Bump secp256k1 from 4.0.3 to 4.0.4 in /examples/stable/demo/hello_world

Bumps [secp256k1](https://github.com/cryptocoinjs/secp256k1-node) from 4.0.3 to 4.0.4.
- [Release notes](https://github.com/cryptocoinjs/secp256k1-node/releases)
- [Commits](cryptocoinjs/secp256k1-node@v4.0.3...v4.0.4)

---
updated-dependencies:
- dependency-name: secp256k1
  dependency-type: indirect
...

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