bug: Could not find a suitable TLS CA certificate bundle

Description
----

Agent has been found in exited status after a certificate error

Supervisor status:

Traceback:
```
[26-03-06 20:25:16] ERROR: (cmd.py:32)| Could not find a suitable TLS CA certificate bundle, invalid path: /srv/testflinger-venv/lib/python3.10/site-packages/certifi/cacert.pem
Traceback (most recent call last):
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/cmd.py", line 27, in main
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/__init__.py", line 146, in start_agent
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/agent.py", line 297, in process_jobs
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/agent.py", line 257, in get_job_data
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/client.py", line 113, in check_jobs
File "/srv/testflinger-venv/lib/python3.10/site-packages/testflinger_agent/client.py", line 233, in get_agent_data
File "/srv/testflinger-venv/lib/python3.10/site-packages/requests/sessions.py", line 602, in get
return self.request("GET", url, **kwargs)
File "/srv/testflinger-venv/lib/python3.10/site-packages/requests/sessions.py", line 589, in request
resp = self.send(prep, **send_kwargs)
File "/srv/testflinger-venv/lib/python3.10/site-packages/requests/sessions.py", line 703, in send
r = adapter.send(request, **kwargs)
File "/srv/testflinger-venv/lib/python3.10/site-packages/requests/adapters.py", line 616, in send
self.cert_verify(conn, request.url, verify, cert)
File "/srv/testflinger-venv/lib/python3.10/site-packages/requests/adapters.py", line 303, in cert_verify
raise OSError(
OSError: Could not find a suitable TLS CA certificate bundle, invalid path: /srv/testflinger-venv/lib/python3.10/site-packages/certifi/cacert.pem
```