Release Zarr-Python v3.4.1

Release: v3.4.1
Scheduled Date: 2026/09/30

Before release:

Check SPEC 0 to see if the minimum supported version of Python or NumPy needs bumping.
Verify that the latest CI workflows on main are passing: Tests, GPU Tests, Hypothesis, Docs, Lint, Wheels.
Run the downstream tests against main: go to the workflow page, click "Run workflow", and select the main branch. Verify that the Xarray and numcodecs integration tests pass.
Open a release PR with the changelog entries for the upcoming release, generated with uv run --only-group release towncrier build --version x.y.z.
Review the release PR and verify the changelog in docs/release-notes.md looks correct.
Merge the release PR.

Release:

Draft a new GitHub Release with tag vX.Y.Z targeting main. Use "Generate release notes" for the description.
Verify the release is published on PyPI and ReadTheDocs.

After release:

Review and merge the pull request on the conda-forge zarr-feedstock that will be automatically generated.

Releasing from a branch other than main

In rare cases (e.g. patch releases for an older minor version), you may need to release from a dedicated release branch (e.g. 3.1.x):

Create the release branch from the appropriate tag if it doesn't already exist.
Cherry-pick or backport the necessary commits onto the branch.
Run towncrier build --version x.y.z and open the release PR against the release branch instead of main.
Run the downstream tests against the release branch instead of main.
When drafting the GitHub Release, set the target to the release branch instead of main.
After the release, ensure any relevant changelog updates are also reflected on main.

xarray downstream tests are failing b/c of changes in xarray preventing tests from running. im going to open a pr that fixes this, then rerun.

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