Fails to start after latest upgrade or dist upgrade

[zmonge]

Describe the bug
Watcher fails to install after installing the last update, or upgrading from Debian Buster to Bullseye

To Reproduce
Steps to reproduce the behavior:

1. Accept update from Watcher main page
2. Wait for update to install & Watcher restart
3. Watcher page fails to load
4. Starting from console, gives the following error:

pi:/opt/Watcher3 $ python3 watcher.py
Connected to database sqlite:////opt/Watcher3/userdata/watcher.sqlite
SQL Database Query: ['PRAGMA user_version'].
Traceback (most recent call last):
File "/opt/Watcher3/core/sqldb.py", line 173, in execute
return self.engine.execute(*command)
AttributeError: 'Engine' object has no attribute 'execute'
SQL Databse Query: ['PRAGMA user_version'].
Traceback (most recent call last):
File "/opt/Watcher3/core/sqldb.py", line 173, in execute
return self.engine.execute(*command)
AttributeError: 'Engine' object has no attribute 'execute'
Traceback (most recent call last):
File "/opt/Watcher3/watcher.py", line 90, in
core.sql.update_database()
File "/opt/Watcher3/core/sqldb.py", line 886, in update_database
v = self.version()
File "/opt/Watcher3/core/sqldb.py", line 873, in version
return self.execute(['PRAGMA user_version']).fetchone()[0]
AttributeError: 'NoneType' object has no attribute 'fetchone'

Expected behavior
Watcher starts successfully after update.

Additional context
Raspberry pi 3B+
Debian 11 Bullseye 6.1.14-v7+ #1633 SMP Thu Mar 2 11:02:03 GMT 2023 armv7l