fix "caddy-frontend: Test bin/trafficserver-logrotate utility"

backports.lzma was missing from dependencies.

software/caddy-frontend/test/setup.py

@@ -52,6 +52,7 @@ setup(name=name,
         # caucase needed to connect to the KeDiFa caucase
         'caucase',
         'cryptography',
+        'backports.lzma',
       ],
       zip_safe=True,
       test_suite='test',