Put the license at the sdist root and check metadata before upload

.github/workflows/publish-pypi.yml

@@ -175,6 +175,11 @@ jobs:
           done
           test "$(ls dist/*.whl | wc -l)" -eq 7 || { echo "::error::expected 7 wheels"; exit 1; }
 
+      # PyPI validates metadata on upload and rejects a file mid-batch, leaving a release with some files and not
+      # others. Checking here fails before anything is uploaded.
+      - name: Check the metadata
+        run: pipx run twine check --strict dist/*
+
       - name: "Dry run: summary"
         if: ${{ inputs.dry_run }}
         run: echo "::notice::DRY RUN — built and checked sister-software-spliterator ${{ needs.check.outputs.version }}; nothing uploaded."

crates/spliterator-py/pyproject.toml

@@ -30,6 +30,9 @@ dev = ["pytest>=8"]
 python-source = "python"
 module-name = "spliterator._native"
 features = ["pyo3/extension-module"]
+# The sdist puts pyproject.toml at its root but this directory's files under crates/spliterator-py/, so the license
+# is also copied to the root, where the `License-File` metadata entry says it is. PyPI rejects an sdist without it.
+include = [{ path = "LICENSE.md", format = "sdist" }]
 
 [tool.ruff]
 line-length = 120