ModuleNotFoundError: No module named 'pkg_resources' after series upgrade to jammy

Hello

After performing series upgrade from focal --> jammy on `mysql-innodb-cluster` charm, facing ModuleNotFoundError error for 'pkg_resources' as shown below:
```logs
2023-08-16 08:51:33 INFO juju.worker.uniter.operation runhook.go:159 ran "update-status" hook (via explicit, bespoke hook script)
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 Traceback (most recent call last):
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 File "/var/lib/juju/agents/unit-mysql-innodb-cluster-1/charm/hooks/update-status", line 7, in
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 from charms.layer import basic # noqa
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 File "/var/lib/juju/agents/unit-mysql-innodb-cluster-1/charm/lib/charms/layer/basic.py", line 6, in
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 from pkg_resources import Requirement
2023-08-16 08:56:20 WARNING unit.mysql-innodb-cluster/1.update-status logger.go:60 ModuleNotFoundError: No module named 'pkg_resources'
2023-08-16 08:56:20 ERROR juju.worker.uniter.operation runhook.go:153 hook "update-status" (via explicit, bespoke hook script) failed: exit status 1
```

series upgrade broke due to this issue and it also affected the other charm units on the same machine like logrotated.
Seems to be an issue of broken package/module requirements in the venv.

Please prioritize as this breaks the series upgrades which are part of larger plan for openstack upgrades in customer environments.

Thanks & regards

Inizia con hooks/update-status e lib/charms/layer/basic.py, dove il traceback mostra che l’importazione di pkg_resources non riesce dopo l’aggiornamento da focal a jammy. Riproduci o esamina i requisiti dei pacchetti dell’ambiente virtuale del charm, quindi verifica che update-status e le unità del charm interessate vengano eseguiti correttamente dopo l’aggiornamento.

Scritto dal modello di indicizzazione a partire dal testo della issue.