Update chunksize test to be robust against key ordering in dicts

Author: jluethi

tests/tasks/test_unit_chunksizes.py

@@ -24,9 +24,9 @@ def test_chunksize_default_with_overrides():
 def test_chunksize_default_with_extra_keys():
     """Test chunksize_default containing invalid keys."""
     chunk_sizes = ChunkSizes(t=5, c=2)
-    chunksize_default = {"a": 100, "b": 200, "c": 1, "x": 2560}
+    chunksize_default = {"a": 100, "c": 1, "x": 2560}
     with pytest.raises(
-        ValueError, match="Invalid keys in chunksize_default: {'a', 'b'}"
+        ValueError, match="Invalid keys in chunksize_default: {'a'}"
     ):
         chunk_sizes.get_chunksize(chunksize_default)