release: 1.5.0: Send-log retention configurable in panel Settings

Send-log retention is configurable from panel **Settings** (global administrator); `SEND_LOG_RETENTION_DAYS` seeds the initial default only.
Added:
  - Panel **Settings** (global administrator): **Send log retention (days)** —
Changed:
  - Deliveries list and delivery detail pages show the configured retention

Full detail: CHANGELOG.md (1.5.0).

deploy/docker-compose.yml

@@ -22,7 +22,7 @@
 
 services:
   selfpost:
-    image: ghcr.io/mixeme/selfpost:1.4.0
+    image: ghcr.io/mixeme/selfpost:1.5.0
     restart: unless-stopped
     environment:
       SELFPOST_HOSTNAME: "${SELFPOST_HOSTNAME:?set the mail/panel hostname, e.g. mail.example.com}"