text: Title: `nest_joins` only works if `join_prefix` is set
  Body: **Describe the bug or question**
  Attributes from a joined model are not nested if no `join_prefix` is set
  
  **To Reproduce**
  
  Consider two simple models, `Hero` and `Ability`
  ```python
  class Ability(Base, UUIDMixin, TimestampMixin, SoftDeleteMixin):
      __tablename__ = "abilities"
  
      name: Mapped[str] = mapped_column(nullable=False)
      strength: Mapped[int] = mapped_column(nullable=False)
      heroes: Mapped[list["Hero"]] = relationship(back_populates="ability")
  
  class Hero(Base, UUIDMixin, TimestampMixin, SoftDeleteMixin):
      __tablename__ = "heroes"
  
      name: Mapped[str] = mapped_column(nullable=False)
      ability_id: Mapped[int] = mapped_column(ForeignKey("abilities.id"))
      ability: Mapped["Ability"] = relationship(back_populates="heroes")
  ```
  
  Then, this code does not work as expected:
  
  ```python
  heroes = await crud_hero.get_multi_joined(db, join_model=Ability, nest_joins=True)
  ```
  
  Returns this (unrelated columns are removed):
  
  ```python
  {
      "data": [
          {
              "name": "Diana",
              "ability_id": UUID("6e52176e-8a92-4a8d-b0b3-1fcd55acc666"),
              "id": UUID("8212bccb-ce20-489a-a675-45772ad60eb8"),
              "name_1": "Superstrength",
              "strength": 10,
              "id_1": UUID("6e52176e-8a92-4a8d-b0b3-1fcd55acc666"),
          },
      ],
      "total_count": 2,
  }
  ```
  
  When adding a prefix, it (kinda) works:
  
  ```python
  heroes = await crud_hero.get_multi_joined(db, join_model=Ability, join_prefix="ability_", nest_joins=True)
  ```
  
  Result is looking better
  
  ```python
  {
      "data": [
          {
              "name": "Diana",
              "ability": {
                  "id": UUID("6e52176e-8a92-4a8d-b0b3-1fcd55acc666"),
                  "name": "Superstrength",
                  "strength": 10,
                  "id_1": UUID("6e52176e-8a92-4a8d-b0b3-1fcd55acc666"),
              },
              "id": UUID("8212bccb-ce20-489a-a675-45772ad60eb8"),
          },
      ],
      "total_count": 2,
  }
  ```
  
  