Use puppet 4 compatible mysql functions

These was introduced in 6.0.0 and is required to
support later version of puppetlabs-mysql.

Change-Id: I81b72476fb2b1315e7d521cbc847ed9f4983da45

manifests/db/mysql.pp

@@ -43,7 +43,7 @@ class monasca::db::mysql {
 
   $user_resource = {
     ensure        => present,
-    password_hash => mysql_password($sql_password),
+    password_hash => mysql::password($sql_password),
     provider      => 'mysql',
     require       => Class['mysql::server'],
   }

metadata.json

@@ -46,6 +46,10 @@
             "name": "maestrodev/wget",
             "version_requirement": ">=0.0.1 <2.0.0"
         },
+        {
+            "name": "puppetlabs/mysql",
+            "version_requirement": ">=6.0.0 <9.0.0"
+        },
         {
             "name": "openstack/keystone",
             "version_requirement": ">=14.2.0 <15.0.0"

releasenotes/notes/puppet4-mysql-func-5a0aec333e429d3f.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    This module now requires a puppetlabs-mysql version >= 6.0.0