ci: attestations

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

.github/workflows/wheel.yml

@@ -27,11 +27,19 @@ jobs:
     environment: pypi
     permissions:
       id-token: write
+      attestations: write
 
     steps:
       - uses: actions/download-artifact@v4
         with:
           name: Packages
           path: dist
 
-      - uses: pypa/gh-action-pypi-publish@release/v1
+    - name: Generate artifact attestation for sdist and wheel
+      uses: actions/attest-build-provenance@v1
+      with:
+        subject-path: "dist/*"
+
+    - uses: pypa/gh-action-pypi-publish@release/v1
+      with:
+        attestations: true