[mgmt] Install passlib in sonic-mgmt docker to support ansible no_log option (sonic-net#2782)

Author: qiluo-msft

dockers/docker-sonic-mgmt/Dockerfile.j2

@@ -45,7 +45,8 @@ RUN pip install ipaddr \
                 pysnmp==4.2.5 \
                 jinja2==2.7.2 \
                 cffi==1.10.0 \
-                paramiko==2.1.2
+                paramiko==2.1.2 \
+                passlib
 
 # Install Microsoft Azure Kusto Library for Python
 RUN pip install azure-kusto-data==0.0.13 \