Bump actions/attest-build-provenance from 1 to 2 (#34)

Author: dependabot[bot]

.github/workflows/py-publish.yml

@@ -32,7 +32,7 @@ jobs:
       run: twine check dist/*
 
     - name: Create attestations
-      uses: actions/attest-build-provenance@v1
+      uses: actions/attest-build-provenance@v2
       with:
         subject-path: 'dist/*'