Use rotated secret in client credentials request

[rplnt]

Related issue

ory/fosite#608

@aeneasr

Proposed changes

This is a followup to the PR above adding usage of the rotated secret for client credentials.

Checklist

• I have read the contributing guidelines
  and signed the CLA.
• 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
  [email protected]) 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).

Further comments

Will update the mod reference once fosite has a tagged release version.

[aeneasr]

Awesome, thank you! 🎉 Your contribution makes Ory better :)