another isolation change

Author: maxrjones

.github/workflows/downstream.yml

@@ -88,7 +88,7 @@ jobs:
         run: |
           uv venv
           uv pip install --group dev
-          uv sync --group dev --group test-zarr-main --no-build-isolation
+          uv sync --group dev --group test-zarr-main
           uv pip install --no-build-isolation -e .
 
       - name: Override zarr-python with branch version