Fix Ruby 2.7 keyword argument warnings

[vasil-nesterov]

This PR fixes Ruby 2.7 keyword argument warnings.

./mongoid-history-0.8.2/lib/mongoid/history/trackable.rb:28: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
./activemodel-6.0.2.2/lib/active_model/callbacks.rb:138: warning: The called method is defined here
./mongoid-history-0.8.2/lib/mongoid/history/trackable.rb:29: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
./activemodel-6.0.2.2/lib/active_model/callbacks.rb:138: warning: The called method is defined here
./mongoid-history-0.8.2/lib/mongoid/history/trackable.rb:30: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
./activemodel-6.0.2.2/lib/active_model/callbacks.rb:138: warning: The called method is defined here

[mongoid-bot]

	1 Warning
⚠️	There’re library changes, but not tests. That’s OK as long as you’re refactoring existing code.

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[coveralls]

Coverage increased (+0.3%) to 98.645% when pulling d9acabb on vasilysn:fix-ruby-27-warnings into 51b1e98 on mongoid:master.