Make chef-vault version pinning optional

attributes/default.rb

@@ -153,4 +153,4 @@ else
   default['sumologic']['collectorRestartCmd'] = "#{default['sumologic']['installDir']}/collector restart"
 end
 
-default['sumologic']['chef_vault_version'] = '2.9.0'
+default['sumologic']['chef_vault_version'] = nil

recipes/sumoconf.rb

@@ -33,7 +33,7 @@ credentials = {}
 
 chef_gem 'chef-vault' do
   compile_time true if respond_to?(:compile_time)
-  version node['sumologic']['chef_vault_version']
+  version node['sumologic']['chef_vault_version'] unless node['sumologic']['chef_vault_version'].nil?
 end
 
 require 'chef-vault'