Incompatibility with version 1.4 and SQLAlchemy<2#351

I recently an issue using sql-continuum==1.4.0 and sql-alchemy==1.4.52. To recreate: ```python from sqlalchemy import create_engine from sqlalchemy.orm import declarative_base import sqlalchemy as sa from sqlalchemy_continuum import make_versioned make_versioned(user_cls=None) Base = declarative_base() class Article(Base): __versioned__ = {} __tablename__ = 'article' id = sa.Column(sa.Integer, primary_key=True, autoincrement=True) sa.orm.configure_mappers() engine = create_engine("sqlite:///tmp.sqlite") connection = engine.connect() connection.execute("BEGIN") ``` gives: ```console /home/ccaveayl/sqlalchemy_continuum_bug/main.py:21: RemovedIn20Warning: Deprecated API features detected! These feature(s) are not compatible with SQLAlchemy 2.0. To prevent incompatible upgrades prior to updating applications, ensure requirements files are pinned to "sqlalchemy<2.0". Set environment variable SQLALCHEMY_WARN_20=1 to show all deprecation warnings. Set environment variable SQLALCHEMY_SILENCE_UBER_WARNING=1 to silence this message. (Background on SQLAlchemy 2.0 at: https://sqlalche.me/e/b8d9) connection.execute("BEGIN") Traceback (most recent call last): File "/home/ccaveayl/sqlalchemy_continuum_bug/main.py", line 21, in <module> connection.execute("BEGIN") File "/home/ccaveayl/sqlalchemy_continuum_bug/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1370, in execute return self._exec_driver_sql( ^^^^^^^^^^^^^^^^^^^^^^ File "/home/ccaveayl/sqlalchemy_continuum_bug/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1669, in _exec_driver_sql ) = self._invoke_before_exec_event( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/ccaveayl/sqlalchemy_continuum_bug/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1506, in _invoke_before_exec_event elem, event_multiparams, event_params = fn( ^^^ File "/home/ccaveayl/sqlalchemy_continuum_bug/.venv/lib/python3.11/site-packages/sqlalchemy/engine/events.py", line 112, in wrap_before_execute orig_fn( File "/home/ccaveayl/sqlalchemy_continuum_bug/.venv/lib/python3.11/site-packages/sqlalchemy_continuum/manager.py", line 436, in track_association_operations if clauseelement.is_insert: ^^^^^^^^^^^^^^^^^^^^^^^ AttributeError: 'str' object has no attribute 'is_insert' ``` As noted in the deprecation warning of the output the `Connection.execute` API was updated to remove use of plain strings. The new API seems to be assumed by `VersioningManager.track_association_operations` leading to a basic incompatibility with SQLAlchemy<2. At present the specified package dependencies for v1.4.0 does not reflect this and I have had to pin sqlalchemy-continuum to <1.4.0 in my environment as other constraints prevent upgrade to SQLAlchemy. I suggest the SQLAlchemy requirement for v1.4.0 be changed to `'SQLAlchemy>=2.0'`.