Bump cryptography from 36.0.1 to 39.0.1 in /examples/postgis

Bumps [cryptography](https://github.com/pyca/cryptography) from 36.0.1 to 39.0.1.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](pyca/cryptography@36.0.1...39.0.1)

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

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