security/rubygem-doorkeeper-openid_connect: update to 1.8.7
Required for gitlab-ce 16.1
Changelog:
https://github.com/doorkeeper-gem/doorkeeper-openid_connect/blob/master/CHANGELOG.md#v187-2023-05-18
(cherry picked from commit a554e1ffab559c98da72992020d6a268047d4a5f)