Bump pynacl from 1.5.0 to 1.6.2 in /lib/poseidon_core

Bumps [pynacl](https://github.com/pyca/pynacl) from 1.5.0 to 1.6.2.
- [Changelog](https://github.com/pyca/pynacl/blob/main/CHANGELOG.rst)
- [Commits](pyca/pynacl@1.5.0...1.6.2)

---
updated-dependencies:
- dependency-name: pynacl
  dependency-version: 1.6.2
  dependency-type: indirect
...

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

Author: dependabot[bot]