databases/redis_exporter: Update 1.89.0 => 1.90.0

While here, add TESTING_UNSAFE since they are failing.

Changelog:
https://github.com/oliver006/redis_exporter/releases/tag/v1.90.0

Commit log:
https://github.com/oliver006/redis_exporter/compare/v1.89.0...v1.90.0

PR: 298051
Reported by: Volodymyr Kostyrko <arcade@b1t.name> (maintainer)
Approved by: osa, vvd (Mentors, implicit)