Fixed serviceproviders 500 status

[Jxlle]

Proposed changes

When using the internal Keyrock authorization registry, it is possible to request whether a subject has the access rights to execute a specific action on a specific resource. Service providers which are allowed to provide services to the subject can also be configured, but querying on this attribute throws an error and returns status code 500 to the user of the api. This PR changes a non-existent method (has) to its implemented equivalent (includes), such that the code doesn't crash anymore.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality
  to not work as expected)

Checklist

• I have read the
  CONTRIBUTING
  doc
• I have signed the
  CLA
• I have added tests that prove my fix is effective or that my feature
  works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream
  modules

Further comments

Problem can also be seen in this forum post: https://spaces.fundingbox.com/spaces/i4trust-i4trust-helpdesk/648daadfb958a4312734000c

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️

[MarkusPfundstein]

+1. Just encounted this issue as well and the fix fixes it