redis-rb 4.8.0 compatibility issues

redis-rb v4.8.0 introduced some changes that generate some deprecation messages in the log files

https://github.com/redis/redis-rb/blob/master/CHANGELOG.md#480

Deprecate sadd and srem returning a boolean when called with a single argument. To enable the redis 5.0 behavior you can set Redis.sadd_returns_boolean = false.

This results in log entries:

Redis#sadd will always return an Integer in Redis 5.0.0. Use Redis#sadd? instead.(called from: /srv/ontoportal/ontologies_api/shared/bundle/ruby/2.7.0/bundler/gems/sparql-client-fb4a89b420f8/lib/sparql/client.rb:450:in `block in query_put_cache')

and

Redis#sadd will always return an Integer in Redis 5.0.0. Use Redis#sadd? instead.(called from: /srv/ontoportal/bundle/ruby/2.7.0/bundler/gems/ontologies_linked_data-4f9139d870c3/lib/ontologies_linked_data/http_cache/cacheable_resource.rb:159:in `cache_write')

ncbo / ontologies_api

redis-rb 4.8.0 compatibility issues #105