Nombre de host de postgres lo pongo en db

src/reymota/settings.py

@@ -87,7 +87,7 @@ DATABASES = {
         "NAME": "reymota",
         "USER": "creylopez",
         "PASSWORD": "Dsa-0213",
-        "HOST": "postgresql",
+        "HOST": "db",
         "PORT": "5432",
     }
 }