chore: enable provenance, remove obsolete NPM token (#218)

See https://docs.npmjs.com/generating-provenance-statements/

Author: chgeo

.github/workflows/release.yml

@@ -37,6 +37,4 @@ jobs:
       with:
         tag: 'v${{ steps.package-version.outputs.current-version }}'
         body: '${{ steps.parse-changelog.outputs.body }}'
-    - run: npm publish --access public
-      env:
-        NODE_AUTH_TOKEN: ${{secrets.npm_token}}
+    - run: npm publish --access public --provenance