Add cbrs_backup.py for downloading enb log

AETHER-2939

Change-Id: Ia95710d23a6db944d47ed4f033d28e81e68daad0
diff --git a/requirements.txt b/requirements.txt
index 5432d5d..3b5f73e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,3 +6,4 @@
 python-jose~=3.3.0
 pylint~=2.7.2
 reuse~=0.11.1
+lxml~=4.6.4