Add AdminCreate schema for admin user creation

Added schema for creating an admin user with a secret.

Author: HarshitWaldia

app/schemas.py

@@ -12,6 +12,11 @@ class UserBase(BaseModel):
 class UserCreate(UserBase):
     password: str
 
+
+class AdminCreate(UserCreate):
+    """Schema for creating an admin user. Includes a server-side secret to authorize admin creation."""
+    admin_secret: str
+
 class UserUpdate(BaseModel):
     name: Optional[str] = None
     phone: Optional[str] = None
@@ -193,4 +198,4 @@ class ShipmentResponse(ShipmentBase):
     id: int
 
     class Config:
-        from_attributes = True
+        from_attributes = True