chore(deps): update mongo:4 docker digest to b905109 (#745)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

docker-compose.yml

@@ -69,7 +69,7 @@ services:
       - 127.0.0.1:$APPEALS_PORT:$APPEALS_PORT
       - 127.0.0.1:$STAFF_PORTAL_PORT:$STAFF_PORTAL_PORT
   db:
-    image: mongo:4@sha256:12ca8c894a12cfedb7d4002f358cfe27933328f99a40571052544e8b4c72e9dd
+    image: mongo:4@sha256:b905109283edf236f514e41353cc67ea7cbe6c13f10864653f197f74e0f27aff
     restart: always
     volumes:
       - ./database:/data/db