minor fix in yaml load with Loader

Change-Id: I1bc0e7197f6057c942490b710fbaf25013202ecb
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>
diff --git a/tests/base.py b/tests/base.py
index c7dad6d..e40338f 100644
--- a/tests/base.py
+++ b/tests/base.py
@@ -108,7 +108,7 @@
 def get_descriptor(descriptor):
     desc = None
     try:
-        tmp = yaml.load(descriptor)
+        tmp = yaml.load(descriptor, Loader=yaml.Loader)
 
         # Remove the envelope
         root = list(tmp.keys())[0]