Fixing du

stat command didn't give proper size. Replacing values with those seen
from failed github actions (4981734, 4969597) caused `python3 -m pytest`
on mac to pass  despite direct calls to `bio2zarr.core.du` returning
4960358, 4955837.

Author: ACEnglish

tests/test_core.py

@@ -237,8 +237,8 @@ def test_examples(self, chunk_size, size, start, stop):
         # It works in CI on Linux, but it'll probably break at some point.
         # It's also necessary to update these numbers each time a new data
         # file gets added
-        ("tests/data", 4957158),
-        ("tests/data/vcf", 4953213),
+        ("tests/data", 4981734),
+        ("tests/data/vcf", 4969597),
         ("tests/data/vcf/sample.vcf.gz", 1089),
     ],
 )