test(bst): Drop Subjects class from context types

Author: effigies

tools/schemacode/tests/test_context_types.py

@@ -20,16 +20,12 @@ def test_assignability() -> None:
 
         uvx --with=. mypy tests
     """
-    subjects: p.Subjects = ctx.Subjects([])
-    subjects = ctx.Subjects([], [])
-
     dataset: p.Dataset = ctx.Dataset(
         dataset_description={},
         tree={},
         ignored=[],
         datatypes=[],
         modalities=[],
-        subjects=subjects,
     )
 
     magnitude: p.Magnitude = ctx.Magnitude("path")