use closed=True in some TypeDict cases

[MarcoGorelli]

closes #3661

this becomes a bit easier to review if you hide whitespace changes: https://github.com/narwhals-dev/narwhals/pull/3800/changes?w=1

i've unpinned mypy/pyrefly from pyproject.toml, as the version used in CI is taken from the lock file anyway, and like this dependabot updates will take care of those updates. note that we need a mypy version more recent than 2.1.0 for this PR to work

Description

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• 💾 Refactor
• ✨ Feature
• 🐛 Bug Fix
• 🔧 Optimization
• 📝 Documentation
• ✅ Test
• 🐳 Other

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• Code follows style guide (ruff)

• Tests added

• Documented the changes

• If this is your first PR to narwhals, attach a screenshot of pytest passing locally (not CI):

  PYTEST_ADDOPTS="--numprocesses=logical" \
  make run-ci DEPS="--extra pandas --extra dask --group core-tests --group sklearn --group plugins" \
  CMD="pytest tests --cov=src --cov=tests --runslow --constructors=pandas,pandas[nullable],pandas[pyarrow],pyarrow,polars[eager],polars[lazy],dask,duckdb,sqlframe"