Allow logging to journald

Fixes #1 (closed)

In addition this fixes following log entries during startup:
    radicale[17897]: [2024-07-03 19:34:50 +0200] [17897] [ERROR] Failed to connect to systemd journal: [Errno 97] Address family not supported by protocol
    radicale[17897]: Traceback (most recent call last):
    radicale[17897]:   File "/usr/lib/python3.12/site-packages/radicale/log.py", line 148, in _try_emit_journal
    radicale[17897]:     journal_socket = socket.socket(
    radicale[17897]:                      ^^^^^^^^^^^^^^
    radicale[17897]:   File "/usr/lib/python3.12/socket.py", line 233, in __init__
    radicale[17897]:     _socket.socket.__init__(self, family, type, proto, fileno)
    radicale[17897]: OSError: [Errno 97] Address family not supported by protocol