Switch to namespace sdtlib functions

puppetlabs-stdlib deprecated the existing functions in favor of
the new stdlib:: functions in 9.0.0. The version was released a few
years ago and now we assume we are ready to adopt to the migration.

Change-Id: I63f3dfb8b2ebc8e378f68f6074ac1080c28e72c3
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

manifests/agent/notification.pp

@@ -151,7 +151,7 @@ class ceilometer::agent::notification (
 
   if $manage_event_pipeline {
     if $event_pipeline_config {
-      $event_pipeline_content = to_yaml($event_pipeline_config)
+      $event_pipeline_content = stdlib::to_yaml($event_pipeline_config)
     } else {
       $event_pipeline_content = template('ceilometer/event_pipeline.yaml.erb')
     }
@@ -177,7 +177,7 @@ class ceilometer::agent::notification (
 
   if $manage_pipeline {
     if $pipeline_config {
-      $pipeline_content = to_yaml($pipeline_config)
+      $pipeline_content = stdlib::to_yaml($pipeline_config)
     } else {
       $pipeline_content = template('ceilometer/pipeline.yaml.erb')
     }

manifests/agent/polling.pp

@@ -339,7 +339,7 @@ Use the identity_name_discovery parameter instead.")
 
   if $manage_polling {
     if $polling_config {
-      $polling_content = to_yaml($polling_config)
+      $polling_content = stdlib::to_yaml($polling_config)
     } else {
       $polling_content = template('ceilometer/polling.yaml.erb')
     }

metadata.json

@@ -11,7 +11,7 @@
         },
         {
             "name": "puppetlabs/stdlib",
-            "version_requirement": ">=5.0.0 <10.0.0"
+            "version_requirement": ">=9.0.0 <10.0.0"
         },
         {
             "name": "openstack/openstacklib",