ci: add github attestations

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

Author: henryiii

.github/workflows/deploy.yml

@@ -19,12 +19,20 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     if: startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      attestations: write
+
     steps:
     - uses: actions/download-artifact@v4
       with:
         name: Packages
         path: dist
 
+    - name: Generate artifact attestation for sdist and wheel
+      uses: actions/attest-build-provenance@v2
+      with:
+        subject-path: "dist/*"
+
     - name: Publish package
       uses: pypa/gh-action-pypi-publish@release/v1
       with: