add install dependencies

.gitignore

@@ -0,0 +1,2 @@
+/src/extra_mailman_archivers.egg-info/
+__pycache__/

setup.cfg

@@ -18,6 +18,8 @@ package_dir =
     = src
 packages = find:
 python_requires = >=3.5
+install_requires =
+    mailman >=3.2.1
 
 [options.packages.find]
 where = src

src/extra_mailman_archivers/monthly_archiver.py

@@ -25,16 +25,12 @@ month.
 """
 
 from contextlib import suppress
-import datetime
-from datetime import timedelta
 from email.utils import parsedate
 import gzip
 import logging
 import os
 import time
 
-from flufl.lock import Lock, TimeOutError
-from mailbox import Maildir
 from mailman.config import config
 from mailman.interfaces.archiver import IArchiver
 from public import public