Replaces yaml.load() with yaml.safe_load()

Yaml.load() return Python object may be dangerous if you receive a YAML
document from an untrusted source such as the Internet. The function
yaml.safe_load() limits this ability to simple Python objects like integers or
lists.

Reference:
https://security.openstack.org/guidelines/dg_avoid-dangerous-input-parsing-libraries.html

Change-Id: I8cff003dad2d0b4ca19b12d45cb5538f683192cd

kb_dib/elements/kloudbuster/post-install.d/99-cloudcfg-edit

@@ -5,7 +5,7 @@ cloudcfg = "/etc/cloud/cloud.cfg"
 user = "cloud-user"
 
 with open(cloudcfg) as f:
-  cfg = yaml.load(f)
+  cfg = safe_yaml.load(f)
 
 try:
   if cfg['system_info']['default_user']['name']: