fix(api): improve signal handling for systemd services

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2331>

changes/changelog.d/improve-signal-handling.bugfix

@@ -0,0 +1 @@
+Improve signal handling for service and containers

deploy/funkwhale-server.service

@@ -9,11 +9,14 @@ User=funkwhale
 WorkingDirectory=/srv/funkwhale/api
 EnvironmentFile=/srv/funkwhale/config/.env
 
+Type=notify
+KillMode=mixed
 ExecStart=/srv/funkwhale/venv/bin/gunicorn \
     config.asgi:application \
     --workers ${FUNKWHALE_WEB_WORKERS} \
     --worker-class uvicorn.workers.UvicornWorker \
     --bind ${FUNKWHALE_API_IP}:${FUNKWHALE_API_PORT}
+ExecReload=/bin/kill -s HUP $MAINPID
 
 [Install]
 WantedBy=multi-user.target