[Doppins] Upgrade dependency Flask-SQLAlchemy to ==2.4

Hi!

A new version was just released of Flask-SQLAlchemy, so Doppins has upgraded your project's dependency ranges.

Make sure that it doesn't break anything, and happy merging! :shipit:

Install or upgrade

Install from PyPI with pip:

pip install -U Flask-SQLAlchemy

Multiple bugs with __tablename__ generation are fixed. Names will be generated for models that define a primary key, but not for single-table inheritance subclasses. Names will not override a declared_attr. PrimaryKeyConstraint is detected. (#541)
Passing an existing declarative_base() as model_class to SQLAlchemy.__init__ will use this as the base class instead of creating one. This allows customizing the metaclass used to construct the base. (#546)
The undocumented DeclarativeMeta internals that the extension uses for binds and table name generation have been refactored to work as mixins. Documentation is added about how to create a custom metaclass that does not do table name generation. (#546)
Model and metaclass code has been moved to a new models module. _BoundDeclarativeMeta is renamed to DefaultMeta; the old name will be removed in 3.0. (#546)
Models have a default repr that shows the model name and primary key. (#530)
Fixed a bug where using init_app would cause connectors to always use the current_app rather than the app they were created for. This caused issues when multiple apps were registered with the extension. (#547)