Bump zarr from 2.18.3 to 2.18.4

Bumps [zarr](https://github.com/zarr-developers/zarr-python) from 2.18.3 to 2.18.4.
- [Release notes](https://github.com/zarr-developers/zarr-python/releases)
- [Changelog](https://github.com/zarr-developers/zarr-python/blob/v2.18.4/docs/release.rst)
- [Commits](zarr-developers/zarr-python@v2.18.3...v2.18.4)

---
updated-dependencies:
- dependency-name: zarr
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -8,7 +8,7 @@ requests==2.32.3
 statsmodels==0.14.4
 pytest==8.3.4
 pytest-cov==6.0.0
-zarr==2.18.3
+zarr==2.18.4
 ruff==0.8.3
 netcdf4==1.7.2
 h5netcdf==1.4.1