Update gh-action-sigstore-python to v2.1.1

Author: stevenclouston

.github/workflows/publish-to-pypi.yml

@@ -100,7 +100,7 @@ jobs:
         name: python-package-distributions
         path: dist/
     - name: Sign the dists with Sigstore
-      uses: sigstore/gh-action-sigstore-python@v1.2.3
+      uses: sigstore/gh-action-sigstore-python@v2.1.1
       with:
         inputs: >-
           ./dist/*.tar.gz
@@ -144,7 +144,7 @@ jobs:
         name: python-package-distributions-testing
         path: dist/
     - name: Sign the dists with Sigstore
-      uses: sigstore/gh-action-sigstore-python@v1.2.3
+      uses: sigstore/gh-action-sigstore-python@v2.1.1
       with:
         inputs: >-
           ./dist/*.tar.gz