refactor build_filter_ensemble to simplify filter creation

lm_eval/filters/__init__.py

 from functools import partial
-from typing import Iterable, List, Optional, Union
+from typing import Optional, Union
 
 from lm_eval.api.filter import FilterEnsemble
 from lm_eval.api.registry import get_filter
@@ -8,18 +8,16 @@ from . import custom, extraction, selection, transformation
 
 
 def build_filter_ensemble(
-    filter_name: str, components: list[tuple[str, Optional[dict]]]
+    filter_name: str,
+    components: list[tuple[str, Optional[dict[str, Union[str, int, float]]]]],
 ) -> FilterEnsemble:
     """
     Create a filtering pipeline.
     """
-    filters = []
-    for function, kwargs in components:
-        if kwargs is None:
-            kwargs = {}
-        # create a filter given its name in the registry
-        f = partial(get_filter(function), **kwargs)
-        # add the filter as a pipeline step
-        filters.append(f)
-
-    return FilterEnsemble(name=filter_name, filters=filters)
+    # create filters given its name in the registry, and add each as a pipeline step
+    return FilterEnsemble(
+        name=filter_name,
+        filters=[
+            partial(get_filter(func), **(kwargs or {})) for func, kwargs in components
+        ],
+    )