SQLAlchemy 2.0 migration of `declarative_base`

[BrianJKoopman]

When running tests in socs I am seeing these warnings:

../../../../../../opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/sotodlib/io/g3thk_db.py:19
  /opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/sotodlib/io/g3thk_db.py:19: MovedIn20Warning: The ``declarative_base()`` function is now available as sqlalchemy.orm.declarative_base(). (deprecated since: 2.0) (Background on SQLAlchemy 2.0 at: https://sqlalche.me/e/b8d9)
    Base = declarative_base()

../../../../../../opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/sotodlib/io/g3tsmurf_db.py:9
  /opt/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/sotodlib/io/g3tsmurf_db.py:9: MovedIn20Warning: The ``declarative_base()`` function is now available as sqlalchemy.orm.declarative_base(). (deprecated since: 2.0) (Background on SQLAlchemy 2.0 at: https://sqlalche.me/e/b8d9)
    Base = declarative_base()

Per the SQLAlchemy 2.0 migration guide, declarative base moved from sqlalchemy.ext.declarative_base to sqlalchemy.orm.delcarative_base.

So I believe instances like this need to be updated with the new import path:

sotodlib/sotodlib/io/g3tsmurf_db.py

Lines 6 to 9 in c1d8b26

	from sqlalchemy.ext.declarative import declarative_base
	from sqlalchemy.orm import sessionmaker, relationship, backref
	Base = declarative_base()