Add support for Ruby 3.0

[Fryguy]

I tried adding Ruby 3.0 support in #18, but it failed with

  1) ForemanApiClient::Connection#operating_system_detail with 2 operating_system details fetches 2 operating_system details
     Failure/Error: PagedResponse.new(@api.resource(resource).action(action).call(filter))

     NoMethodError:
       undefined method `escape' for URI:Module
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/route.rb:23:in `block in path'
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/route.rb:20:in `each'
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/route.rb:20:in `inject'
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/route.rb:20:in `path'
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/api.rb:163:in `call'
     # ./vendor/bundle/ruby/3.0.0/gems/apipie-bindings-0.0.15/lib/apipie_bindings/action.rb:14:in `call'
     # ./lib/foreman_api_client/connection.rb:49:in `fetch'
     # ./lib/foreman_api_client/connection.rb:42:in `block in load_details'
     # ./lib/foreman_api_client/paged_response.rb:28:in `map'
     # ./lib/foreman_api_client/paged_response.rb:28:in `map!'
     # ./lib/foreman_api_client/connection.rb:42:in `load_details'
     # ./lib/foreman_api_client/connection.rb:38:in `all_with_details'
     # ./spec/connection_spec.rb:36:in `block (4 levels) in <top (required)>'
     # ./spec/connection_spec.rb:40:in `block (5 levels) in <top (required)>'
     # ./spec/spec_helper.rb:9:in `block in with_vcr'
     # ./vendor/bundle/ruby/3.0.0/gems/vcr-3.0.3/lib/vcr/util/variable_args_block_caller.rb:9:in `call_block'
     # ./vendor/bundle/ruby/3.0.0/gems/vcr-3.0.3/lib/vcr.rb:189:in `use_cassette'
     # ./spec/spec_helper.rb:8:in `with_vcr'
     # ./spec/connection_spec.rb:39:in `block (4 levels) in <top (required)>'

https://github.com/Fryguy/foreman_api_client/runs/5840655737?check_suite_focus=true

Part of ManageIQ/manageiq#21536