fix: fix circular import in KeyValueStore (#805)

### Description

- Fix circular imports occurring after using `service_container` in
`KeyValueStore`

### Issues

- Closes: #804

### Checklist

- [ ] CI passed

Author: Mantisus

src/crawlee/storages/_key_value_store.py

@@ -4,7 +4,6 @@
 
 from typing_extensions import override
 
-from crawlee import service_container
 from crawlee._utils.docs import docs_group
 from crawlee.base_storage_client._models import KeyValueStoreKeyInfo, KeyValueStoreMetadata
 from crawlee.events._types import Event, EventPersistStateData
@@ -16,6 +15,7 @@
     from crawlee._types import JsonSerializable
     from crawlee.base_storage_client import BaseStorageClient
     from crawlee.configuration import Configuration
+    from crawlee.events._event_manager import EventManager
 
 T = TypeVar('T')
 
@@ -226,12 +226,18 @@ async def _persist_save(self, _event_data: EventPersistStateData | None = None)
         for key, value in self._cache.items():
             await self.set_value(key, value)
 
+    def _get_event_manager(self) -> EventManager:
+        """Get event manager from crawlee services."""
+        from crawlee.service_container import get_event_manager
+
+        return get_event_manager()  # type: ignore[no-any-return] # Mypy is broken
+
     def _ensure_persist_event(self) -> None:
         """Setup persist state event handling if not already done."""
         if self._persist_state_event_started:
             return
 
-        event_manager = service_container.get_event_manager()
+        event_manager = self._get_event_manager()
         event_manager.on(event=Event.PERSIST_STATE, listener=self._persist_save)
         self._persist_state_event_started = True
 
@@ -242,7 +248,7 @@ def _clear_cache(self) -> None:
     def _drop_persist_state_event(self) -> None:
         """Off event_manager listener and drop event status."""
         if self._persist_state_event_started:
-            event_manager = service_container.get_event_manager()
+            event_manager = self._get_event_manager()
             event_manager.off(event=Event.PERSIST_STATE, listener=self._persist_save)
         self._persist_state_event_started = False