Use URI.open intead of Kernel#open

Signed-off-by: Shizuo Fujita <[email protected]>

Author: Watson1978

lib/fluent/plugin/filter_obsolete_plugins.rb

@@ -32,7 +32,7 @@ class ObsoletePluginsFilter < Fluent::Plugin::Filter
       def configure(conf)
         super
 
-        @obsolete_plugins = open(@obsolete_plugins_yml) do |io|
+        @obsolete_plugins = URI.open(@obsolete_plugins_yml) do |io|
           YAML.safe_load(io.read)
         end