provision: seed loader with state.conf.memory_seed_loaders

Ensure that the provision environment config is available _before_ attempting
to load it, otherwise `base` will take the default resulting in values from the
testenv being inadvertently inherited.

Author: masenf

src/tox/provision.py

@@ -97,6 +97,7 @@ def add_tox_requires_min_version(reqs: list[Requirement]) -> list[Requirement]:
         recreate=state.conf.options.recreate and not state.conf.options.no_recreate_provision,
     )
     provision_tox_env: str = state.conf.core["provision_tox_env"]
+    state.conf.memory_seed_loaders[provision_tox_env].append(loader)
     state.envs._mark_provision(bool(missing), provision_tox_env, loader)
 
     from tox.plugin.manager import MANAGER