Bump sigstore/gh-action-sigstore-python to 3.1.0

Updated version of sigstore/gh-action-sigstore-python in CI/CD.

Author: tpvasconcelos

docs/reference/changelog.md

@@ -9,6 +9,7 @@ Unreleased changes
 
 - Bump actions/download-artifact from 5 to 6 ({gh-pr}`354`)
 - Bump actions/upload-artifact from 4 to 5 ({gh-pr}`353`)
+- Bump sigstore/gh-action-sigstore-python from 3.0.1 to 3.1.0 ({gh-pr}`352`)
 
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