Allow non-root to within container to access the secret

compose.yaml

@@ -15,7 +15,9 @@ services:
       - TZ=Europe/Helsinki
       - PYTHONUNBUFFERED=1
     secrets:
-      - discord_token
+      - source: discord_token
+        target: discord_token
+        mode: 0444   # allow non-root reads
     volumes:
       - ./data:/app/data
       - ./src:/app/src:ro