Use of yaml.safe_load instead of yaml_load

Change-Id: Ibdb89b23560f2c587f554f11f0e2a577047e6e22
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/osm_pla/config/config.py b/osm_pla/config/config.py
index 13ff43b..2fd7a8b 100644
--- a/osm_pla/config/config.py
+++ b/osm_pla/config/config.py
@@ -35,7 +35,7 @@
             path = "pla.yaml"
             config_file = pkg_resources.resource_filename(__name__, path)
         with open(config_file) as f:
-            self.conf = yaml.load(f)
+            self.conf = yaml.safe_load(f)
 
     def _read_env(self):
         for env in os.environ: