### Bug Description When running subprocesses within the charm code, the Juju Python virtual environment `/var/lib/juju/agents/unit-landscape-server-0/charm/venv/` is included in the system’s PYTHONPATH. This causes conflicts, as we need to use the system Python and its dependencies, not those from the Juju environment. For example this bug https://bugs.launchpad.net/landscape-charm/+bug/2076926, installing a later version of the pydantic package via apt doesn't do anything because the version from the Juju charm virtual environment takes precedence. A similar issue occurred with the distutils package, where the system version was overshadowed. ### To Reproduce We used this workaround to make sure the system Python paths are used by removing Juju's virtual environment from PYTHONPATH before invoking subprocesses: ```python def get_modified_env_vars(): """ Because the python path gets munged by the juju env, this grabs the current env vars and returns a copy with the juju env removed from the python paths """ env_vars = os.environ.copy() logging.info("Fixing python paths") new_paths = [path for path in sys.path if "juju" not in path] env_vars["PYTHONPATH"] = ":".join(new_paths) return env_vars subprocess.check_call(call, env=get_modified_env_vars()) ``` ### Environment 22.04 juju --version 3.5.3-genericlinux-amd64 ### charmcraft.yaml ```yaml N/a ``` ### Relevant log output ```shell 2024-08-13 08:25:19 WARNING unit.landscape-server/0.db-relation-changed logger.go:60 from canonical.landscape.model.main.oidc import ( 2024-08-13 08:25:19 WARNING unit.landscape-server/0.db-relation-changed logger.go:60 File "/opt/canonical/landscape/canonical/landscape/model/main/oidc.py", line 6, in <module> 2024-08-13 08:25:19 WARNING unit.landscape-server/0.db-relation-changed logger.go:60 from pydantic import AnyUrl, BaseModel, Field, model_validator 2024-08-13 08:25:19 WARNING unit.landscape-server/0.db-relation-changed logger.go:60 ImportError: cannot import name 'model_validator' from 'pydantic' (/var/lib/juju/agents/unit-landscape-server-0/charm/venv/pydantic/__init__.py) 2024-08-13 08:25:19 ERROR unit.landscape-server/0.juju-log server.go:325 db:8: Landscape Server schema update failed with return code 1 ```