Enable more tskit tests on Windows

Author: jeromekelleher

tests/test_tskit_data.py

@@ -19,10 +19,6 @@
 from vcztools.plink import write_plink
 from vcztools.vcf_writer import write_vcf
 
-pytestmark = pytest.mark.skipif(
-    sys.platform == "win32", reason="Not supported on Windows"
-)
-
 
 def add_mutations(ts):
     # Add some mutation to the tree sequence. This guarantees that
@@ -211,6 +207,7 @@ def fx_simple_ts(tmp_path):
 # handled)
 
 
+@pytest.mark.skipIf(sys.platform == "win32", reason="Not supported on Windows")
 class TestVcfRoundTrip:
     def assert_bio2zarr_rt(self, tmp_path, tskit_vcz):
         vcf_path = tmp_path / "out.vcf"