Fix startup issue with postgres on first start. Implement health check of postgres and delay django container until it's healthy.

compose.yaml

@@ -20,7 +20,8 @@ services:
     networks:
       - backendnet
     depends_on:
-      - "shimatta-kenkyusho-db"
+      shimatta-kenkyusho-db:
+        condition: service_healthy
 
   shimatta-kenkyusho-db:
     image: postgres:16.5-alpine
@@ -31,6 +32,11 @@ services:
       - "${PGDATA:-./run/pgdata}:/var/lib/postgresql/data"
     networks:
       - backendnet
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
 
 networks:
   backendnet: