Update minimum version of logstash-mixin-aws to support assume-role

Fixes #51, #39

Author: lukewaite

logstash-input-cloudwatch_logs.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-mixin-aws', '>= 4.0.0'
+  s.add_runtime_dependency 'logstash-mixin-aws', '>= 4.3.0'
   s.add_runtime_dependency 'stud', '~> 0.0.22'
 
   s.add_development_dependency 'logstash-devutils'