fix: re-wire zarr-metadata up as a dependency for zarr-python

Author: d-v-b

pyproject.toml

@@ -154,6 +154,9 @@ hooks.vcs.version-file = "src/zarr/_version.py"
 
 [tool.hatch.envs.test]
 dependency-groups = ["test"]
+extra-dependencies = [
+    "zarr-metadata @ {root:uri}/packages/zarr-metadata",
+]
 
 [tool.hatch.envs.test.env-vars]