revert to processes

src/okipy/strategies.py

@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from multiprocessing.pool import ThreadPool
+from multiprocessing.pool import Pool
 from typing import Callable, TypeVar
 
 
@@ -17,7 +17,7 @@ class RunStrategy:
 class Parallel(RunStrategy):
     procs: None | int = None
     def run_all(self, items: list[T], oper: Callable[[T], O]) -> list[O]:
-        return ThreadPool(self.procs).map(oper, items)
+        return Pool(self.procs).map(oper, items)
 
 
 class Sequential(RunStrategy):