Fix v6 (#428)

*  Copy working setup from master

* Remove unused configuration (rspec-retry)

* Fix broken specs

* Make specs more reliable

* Fix sidekiq develop (#426)

* Mandatory rubocop commit

* Allow failures on sidekiq.develop

# Conflicts:
#	lib/sidekiq_unique_jobs/version_check.rb
#	spec/sidekiq_unique_jobs/key_spec.rb

* Mandatory rubocop commit

* Fix tests

* Update ruby versions

Takes care of some security breaches

* Prevent JRuby from using Pry

* Use pry for jruby

* Use fake irb too for the sake of jfuckingruby

* Make testing of console_class.start work

* Mandatory rubocop commit

* Another mandatory rubocop commit

* Include .simplecov with rubocop

* Cleanup after experiments

* Unfortunately truffleruby is sooooo slooooow

* Update rubocop 💣

* Fix compatibility with Sidekiq 6.0. logger

* Fix .yardopts

* Improve performance by avoiding the block arg

* Close #419

lib/sidekiq_unique_jobs/logging.rb

@@ -16,6 +16,7 @@ def logger
     #   Used for compatibility with logger
     def log_debug(message_or_exception = nil, &block)
       logger.debug(message_or_exception, &block)
+      nil
     end
 
     # Logs a message at info level
@@ -24,6 +25,7 @@ def log_debug(message_or_exception = nil, &block)
     #   Used for compatibility with logger
     def log_info(message_or_exception = nil, &block)
       logger.info(message_or_exception, &block)
+      nil
     end
 
     # Logs a message at warn level
@@ -32,6 +34,7 @@ def log_info(message_or_exception = nil, &block)
     #   Used for compatibility with logger
     def log_warn(message_or_exception = nil, &block)
       logger.warn(message_or_exception, &block)
+      nil
     end
 
     # Logs a message at error level
@@ -48,6 +51,7 @@ def log_error(message_or_exception = nil, &block)
     #   Used for compatibility with logger
     def log_fatal(message_or_exception = nil, &block)
       logger.fatal(message_or_exception, &block)
+      nil
     end
 
     def logging_context(middleware_class, job_hash)