Update sigstore/gh-action-sigstore-python action to v3

Author: renovate[bot]

.github/workflows/main.yml

@@ -96,7 +96,7 @@ jobs:
           name: python-package-distributions
           path: dist/
       - name: Sign the dists with Sigstore
-        uses: sigstore/gh-action-sigstore-python@v2.1.1
+        uses: sigstore/gh-action-sigstore-python@v3.0.0
         with:
           inputs: >-
             ./dist/*.tar.gz