Pin python-dateutils to latest py2-compatible

PROD-37288

Change-Id: Ifbe3b967ad73fed5d4de77bf29aa7359adbca451
diff --git a/requirements.txt b/requirements.txt
index 30efd89..6671953 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+python-dateutil==2.8.2
 paramiko>=1.16.0,<2.0.1
 PyYAML==3.13
 six>=1.9.0