Change default number of workers to three

lisainstrument/containers.py

@@ -31,7 +31,7 @@ class ForEachObject(abc.ABC):
             self.dict = {mosa: values[mosa] for mosa in self.indices()}
         elif callable(values):
             if concurrent:
-                with ThreadPoolExecutor() as executor:
+                with ThreadPoolExecutor(max_workers=3) as executor:
                     indices = self.indices()
                     computed_values = executor.map(values, indices)
                     self.dict = dict(zip(indices, computed_values))