Fix mongo dependency test suite (#1668)

Author: MaicolBen

devise_token_auth.gemspec

@@ -31,5 +31,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'pg'
   s.add_development_dependency 'mysql2'
   s.add_development_dependency 'mongoid', '>= 4', '< 8'
-  s.add_development_dependency 'mongoid-locker', '~> 2.0'
+  s.add_development_dependency 'mongoid-locker', '>= 1.0', '< 3.0'
 end