Bug Description

When a new .py file is added to a git-based custom playbook repository and a config reload is triggered (via FileSystemWatcher detecting changes to the playbooks config or playbooks directory), the new module is not discovered by pkgutil.walk_packages(). The new action only becomes available after a full pod restart.

Changes to existing files work fine — importlib.reload() picks them up. Only newly added files are affected.

Root Cause

In ConfigLoader.__import_playbooks_package() (src/robusta/runner/config_loader.py), after pip install copies new files to site-packages, pkgutil.walk_packages() relies on Python's FileFinder to enumerate modules. The FileFinder caches directory listings from the initial import at process startup. Since importlib.invalidate_caches() is never called, newly installed .py files remain invisible to the finder machinery.

From the Python docs:

If you are dynamically importing a module that was created since the interpreter began execution (e.g., created a Python source file), you may need to call this function in order to notice the new module.

Steps to Reproduce

1. Configure a git-based custom playbook repo in Robusta
2. Let the runner start and load the initial set of actions
3. Add a new .py file with a new action to the git repo and push
4. Trigger a config reload (e.g., update the robusta-playbooks-config-secret)
5. Observe that the new action is not registered — only existing actions are reloaded
6. Restart the pod — the new action is now available

Expected Behavior

New playbook modules added to git repos should be discovered and loaded during hot reload without requiring a pod restart.

Proposed Fix

Add importlib.invalidate_caches() before the pkgutil.walk_packages() call in __import_playbooks_package().