[BUG] Upgrade to 1.6.14 backup failed "Error while executing bwcli"

### What happened?

When doing the Upgrade described here (https://docs.bunkerweb.io/latest/upgrading/#procedure) from `1.6.13 -> 1.6.14` the updater was not able to create a backup but still did go on with the upgrade. Afterwards I needed to restart the server a few times in order to again have access to sites served and control panel.

### How to reproduce?

```
LATEST_VERSION=$(curl -s https://api.github.com/repos/bunkerity/bunkerweb/releases/latest | grep -oP '"tag_name": "\K(.*)(?=")')

# Download the script and its checksum
curl -fsSL -O https://github.com/bunkerity/bunkerweb/releases/download/${LATEST_VERSION}/install-bunkerweb.sh
curl -fsSL -O https://github.com/bunkerity/bunkerweb/releases/download/${LATEST_VERSION}/install-bunkerweb.sh.sha256

# Verify the checksum
sha256sum -c install-bunkerweb.sh.sha256

# If the check is successful, run the script
chmod +x install-bunkerweb.sh
sudo ./install-bunkerweb.sh

=========================================
BunkerWeb Easy Install Script
=========================================

[INFO] Detected OS: Ubuntu 24.04
[INFO] Fetching gum 0.17.0 (Linux_x86_64) from GitHub releases...
[INFO] Existing Linux installation detected — keeping the Linux deployment.
[INFO] Detected existing BunkerWeb installation (version 1.6.13)
[INFO] Detected install type: Full Stack (bunkerweb + scheduler + ui)
[WARNING] Requested version 1.6.14 differs from installed version 1.6.13. Upgrade will be attempted.
▸ Upgrade BunkerWeb: [Yes]
[INFO] Applying detected install type: Full Stack (bunkerweb + scheduler + ui)

▸ 💾 Pre-upgrade Backup
╭──────────────────────────────────────────────────────────────────────────────╮
│ A pre-upgrade backup is recommended to preserve │
│ configuration and database state. The backup runs before any │
│ package upgrade and is stored under the path you choose below. │
╰──────────────────────────────────────────────────────────────────────────────╯

▸ Pre-upgrade Backup: [Yes]
▸ Pre-upgrade Backup: [/var/tmp/bunkerweb-backup-20260824-162033]

```

### Configuration file(s) (yaml or .env)

```YAML

```

### Relevant log output

```shell
[INFO] Upgrade mode: 1.6.13 -> 1.6.14
[STEP] Creating pre-upgrade backup in /var/tmp/bunkerweb-backup-20260824-162033
[2026-08-24 16:20:36 +0200] [CLI] [2522655] [ℹ️ ] - Getting variables from database
[2026-08-24 16:20:36 +0200] [CLI] [2522655] [ℹ️ ] - ✅ Database connection established
[2026-08-24 16:20:36 +0200] [CLI] [2522655] [❌] - Error while executing bwcli :
Traceback (most recent call last):
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1969, in _exec_single_context
self.dialect.do_execute(
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/default.py", line 952, in do_execute
cursor.execute(statement, parameters)
sqlite3.OperationalError: no such table: bw_settings

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/share/bunkerweb/cli/main.py", line 76, in
cli = CLI()
^^^^^
File "/usr/share/bunkerweb/cli/CLI.py", line 105, in __init__
self.__variables = self.__db.get_config()
^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/db/Database.py", line 105, in wrapper
return func(self, *args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/db/Database.py", line 2816, in get_config
for setting in query:
File "/usr/share/bunkerweb/deps/python/sqlalchemy/orm/query.py", line 2850, in __iter__
result = self._iter()
^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/orm/query.py", line 2864, in _iter
result: Union[ScalarResult[_T], Result[_T]] = self.session.execute(
^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/orm/session.py", line 2373, in execute
return self._execute_internal(
^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/orm/session.py", line 2271, in _execute_internal
result: Result[Any] = compile_state_cls.orm_execute_statement(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/orm/context.py", line 306, in orm_execute_statement
result = conn.execute(
^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1421, in execute
return meth(
^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/sql/elements.py", line 526, in _execute_on_connection
return connection._execute_clauseelement(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1643, in _execute_clauseelement
ret = self._execute_context(
^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1848, in _execute_context
return self._exec_single_context(
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1988, in _exec_single_context
self._handle_dbapi_exception(
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 2365, in _handle_dbapi_exception
raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/base.py", line 1969, in _exec_single_context
self.dialect.do_execute(
File "/usr/share/bunkerweb/deps/python/sqlalchemy/engine/default.py", line 952, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: bw_settings
[SQL: SELECT bw_settings.id AS bw_settings_id, bw_settings.context AS bw_settings_context, bw_settings."default" AS bw_settings_default, bw_settings.multiple AS bw_settings_multiple
FROM bw_settings ORDER BY bw_settings."order"]
(Background on this error at: https://sqlalche.me/e/20/e3q8)

[WARNING] Automatic backup failed. Verify manually before continuing.
[INFO] Removing holds (bunkerweb, nginx)
[STEP] Stopping services prior to upgrade
[CMD] systemctl stop bunkerweb
[CMD] systemctl stop bunkerweb-ui
[CMD] systemctl stop bunkerweb-scheduler
[STEP] Upgrading BunkerWeb package
```

### BunkerWeb version

1.6.14

### What integration are you using?

Linux

### Linux distribution (if applicable)

Ubuntu 24.04.4 LTS

### Removed private data

- [x] I have removed all private data from the configuration file and the logs

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct