[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

mesa/experimental/signals/signal.py

@@ -17,9 +17,7 @@
 _hashable_signal = namedtuple("_HashableSignal", "instance name")
 
 CURRENT_COMPUTED: Computed | None = None  # the current Computed that is evaluating
-PROCESSING_SIGNALS: set[tuple[str,]] = (
-    set()
-)
+PROCESSING_SIGNALS: set[tuple[str,]] = set()
 
 
 class BaseObservable(ABC):
@@ -108,7 +106,6 @@ def __set__(self, instance: HasObservables, value):  # noqa D103
 class Computable(BaseObservable):
     """A Computable that is depended on one or more Observables.
 
-
     .. code-block:: python
 
        class MyAgent(Agent):