Use latest stable mongo driver and fix the bug where BigDecimal.from_bson is calling an undefined method

Author: sdmeisner

lib/logstash/outputs/bson/big_decimal.rb

@@ -44,7 +44,7 @@ module ClassMethods
       # @return [ BigDecimal ] The decoded BigDecimal.
       # @see http://bsonspec.org/#/specification
       def from_bson(bson)
-        from_bson_double(bson.read(8))
+        from_bson_double(bson.get_bytes(8))
       end
 
       private

logstash-output-mongodb.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |s|
   # Gem dependencies
   s.add_runtime_dependency "logstash-core-plugin-api", ">= 1.60", "<= 2.99"
   s.add_runtime_dependency 'logstash-codec-plain'
-  s.add_runtime_dependency 'mongo', '~> 2.0.6'
+  s.add_runtime_dependency 'mongo', '~> 2.6'
 
   s.add_development_dependency 'logstash-devutils'
 end