client: change pk field to int64

[pike1212]

Related issue

#1595

Proposed changes

Changed PK from int to int64, ran make test with no issues.

Checklist

• I have read the contributing guidelines
• I have read the security policy
• I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security
  vulnerability, I confirm that I got green light (please contact security@ory.sh) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation within the code base (if appropriate)
• I have documented my changes in the developer guide (if appropriate)

[CLAassistant]

)))))))))))))))))))))))
All committers have signed the CLA.

[aeneasr]

Thank you!