(Temporarily) specify sqlalchemy<2.0.0.

SQLAlchemy 2 has introduced several breaking changes that can break
several things in the application - especially where the code uses
`connection.execute()` with raw SQL statements.

We need to temporarily force the installation of versions from the 1.x
branch, while migrating the existing code to the new version.

requirements.txt

@@ -12,10 +12,10 @@ python-dateutil
 tz
 frozendict
 requests
-sqlalchemy
+sqlalchemy<2.0.0
 bcrypt
 rsa
-zeroconf
+zeroconf>=0.27.0
 paho-mqtt
 websocket-client
 croniter

setup.py

@@ -57,7 +57,7 @@ setup(
         'redis',
         'requests',
         'croniter',
-        'sqlalchemy',
+        'sqlalchemy<2.0.0',
         'websockets',
         'websocket-client',
         'wheel',