SA20: Adjust compatible SQLAlchemy versions: >=1.4,<2.1

The code, now ready for SQLAlchemy 2.x, will not be compatible with
SQLAlchemy 1.3 any longer.

The reason is that `sqlalchemy.orm.declarative_base` did not exist back
then.

Author: amotl

.github/workflows/tests.yml

@@ -22,7 +22,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
         cratedb-version: ['5.1.2']
-        sqla-version: ['1.3.24', '1.4.45', 'next']
+        sqla-version: ['1.4.45', 'next']
       fail-fast: false
     env:
       CRATEDB_VERSION: ${{ matrix.cratedb-version }}

README.rst

@@ -46,7 +46,7 @@ A Python client library for CrateDB_.
 This library:
 
 - Implements the Python `DB API 2.0`_ specification
-- Includes support for SQLAlchemy_ (>= 1.3.0)
+- Includes support for SQLAlchemy_ >= 1.4.
 
 Prerequisites
 =============

setup.py

@@ -60,7 +60,7 @@ def read(path):
     },
     install_requires=['urllib3>=1.9,<2'],
     extras_require=dict(
-        sqlalchemy=['sqlalchemy>=1.0,<1.5',
+        sqlalchemy=['sqlalchemy>=1.4,<2.1',
                     'geojson>=2.5.0,<3',
                     'backports.zoneinfo<1; python_version<"3.9"'],
         test=['tox>=3,<4',