Require bson >= 4.2.1 and limit it to < 5.0.0

Author: estolfo

mongo.gemspec

@@ -30,5 +30,5 @@ Gem::Specification.new do |s|
   s.has_rdoc          = 'yard'
   s.bindir            = 'bin'
 
-  s.add_dependency 'bson', '~> 4.2'
+  s.add_dependency 'bson', '>=4.2.1', '<5.0.0'
 end