set default version for debian buster and add support for buster

debian buster was released on july 6th and many folks are already
deploying it. This module should start supporting the new debian stable
version.

For this, we need the module to know what the new default PHP version is
for this new release.

Closes: #529

Author: lelutin

manifests/globals.pp

@@ -28,7 +28,8 @@
 
   $default_php_version = $facts['os']['name'] ? {
     'Debian' => $facts['os']['release']['major'] ? {
-      '9' => '7.0',
+      '9'     => '7.0',
+      '10'    => '7.3',
       default => '5.x',
     },
     'Ubuntu' => $facts['os']['release']['major'] ? {

metadata.json

@@ -48,7 +48,8 @@
       "operatingsystem": "Debian",
       "operatingsystemrelease": [
         "8",
-        "9"
+        "9",
+        "10"
       ]
     },
     {