Update HDMF 4.2.0 release date and changelog

[rly]

Prepare for release of HDMF 4.2.0

Before merging:

• Make sure all PRs to be included in this release have been merged to dev.
• Major and minor releases: Update dependency ranges in pyproject.toml as needed.
• Check legal file dates and information in Legal.txt, license.txt, README.rst, docs/source/conf.py,
  and any other locations as needed
• Update pyproject.toml as needed
• Update README.rst as needed
• Update src/hdmf/common/hdmf-common-schema submodule as needed. Check the version number and commit SHA
  manually. Make sure we are using the latest release and not the latest commit on the main branch.
• Update changelog (set release date) in CHANGELOG.md and any other docs as needed
• Run tests locally including gallery tests, and inspect all warnings and outputs
  (pytest && python test_gallery.py). Try to remove all warnings.
• Run PyNWB tests locally including gallery and validation tests, and inspect all warnings and outputs
  (cd pynwb; git checkout dev; git pull; python test.py -v > out.txt 2>&1)
• Run HDMF-Zarr tests locally including gallery and validation tests, and inspect all warnings and outputs
  (cd hdmf-zarr; git checkout dev; git pull; pytest && python test_gallery.py)
• Test docs locally and inspect all warnings and outputs cd docs; make clean && make html
• After pushing this branch to GitHub, manually trigger the "Run all tests" GitHub Actions workflow on this
  branch by going to https://github.com/hdmf-dev/hdmf/actions/workflows/run_all_tests.yml, selecting
  "Run workflow" on the right, selecting this branch, and clicking "Run workflow". Make sure all tests pass.
• Check that the readthedocs build for this PR succeeds (see the PR check)

After merging:

1. Create release by following steps in docs/source/make_a_release.rst or use alias git pypi-release [tag] if set up
2. After the CI bot creates the new release (wait ~10 min), update the release notes on the
   GitHub releases page with the changelog
3. Check that the readthedocs "stable" build runs and succeeds
4. Either monitor conda-forge/hdmf-feedstock for the
   regro-cf-autotick-bot bot to create a PR updating the version of HDMF to the latest PyPI release, usually within
   24 hours of release, or manually create a PR updating recipe/meta.yaml with the latest version number
   and SHA256 retrieved from PyPI > HDMF > Download Files > View hashes for the .tar.gz file. Re-render and
   update the dependencies as needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.44%. Comparing base (693621d) to head (0f6ae76).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #1362   +/-   ##
=======================================
  Coverage   92.44%   92.44%           
=======================================
  Files          42       42           
  Lines        9747     9747           
  Branches     1979     1979           
=======================================
  Hits         9011     9011           
  Misses        462      462           
  Partials      274      274           

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[rly]

I was hoping to get other PRs merged before a 4.2.0 release but the unreleased fix on string validation is blocking a project, so we would like to get it and the other changes currently on dev released sooner.

[rly]

NOTE: In the run all tests workflow, the tests that install optional dependencies fail due to an incompatibility between sssom, a dependency of oaklib, and pandas==3.0.0rc0. I created an issue there: mapping-commons/sssom-py#637