Consider removing upper version bound on sqlalchemy

[tapetersen]

Describe the bug

Currently the project is limiting the upper version of sqlalchemy to <2.1 which makes it hard to use and actually test the library against the newer release.

SQLalchemy is usually extremely good in keeping backwards-compatibility and in the cases where it breaks it's much easier for an application to add it's own constraint than it its to override a bound in a library.

To Reproduce

Steps to reproduce the behavior:
Try to install SQLAlchemy 2.1.0b2 in a project using fastapi-users-db-sqlalchemy
uv sync --upgrade-package SQLAlchemy==2.1.0b2

Because only fastapi-users-db-sqlalchemy<=7.0.0 is available and fastapi-users-db-sqlalchemy==7.0.0 depends on sqlalchemy[asyncio]>=2.0.0,<2.1.0, we can conclude that fastapi-users-db-sqlalchemy>=7.0.0 depends on sqlalchemy>=2.0.0,<2.1.0.
      And because fastapi-users[sqlalchemy]==14.0.1 depends on fastapi-users-db-sqlalchemy>=7.0.0, we can conclude that fastapi-users[sqlalchemy]==14.0.1 depends on sqlalchemy>=2.0.0,<2.1.0.
      And because we know from (11) that all of:
          fastapi-users[sqlalchemy]>=12.1.3,<14.0.1
          fastapi-users[sqlalchemy]>14.0.1
      depend on sqlalchemy>=2.0.0,<2.1.0, we can conclude that fastapi-users[sqlalchemy]>=12.1.3 depends on sqlalchemy>=2.0.0,<2.1.0.
      And because application depends on fastapi-users[sqlalchemy]>=12.1.3, we can conclude that application depends on sqlalchemy>=2.0.0,<2.1.0.
      And because we know from (1) that application depends on sqlalchemy==2.1.0b2, we can conclude that applications requirements are unsatisfiable.
      And because your workspace requires application, we can conclude that your workspace's requirements are unsatisfiable.

Expected behavior

Package installs with a newer version of SQLAlchemy that sure maybe will have compatibility issues but right now the upper version bound results in guaranteed incompatibility even if no actual problems exists

Configuration

• Python version : 3.12
• FastAPI version : v0.115.12
• FastAPI Users version : v14.0.1

FastAPI Users configuration

# Please copy/paste your FastAPI Users configuration here.

Additional context

Add any other context about the problem here.