PYSEC-2026-1923 sigstore has insufficient validation of integration timestamp during verification

Summary Versions of sigstore-python newer than 2.0.0 but prior to 3.6.0 perform insufficient validation of the "integration time" present in "v2" and "v3" bundles during the verification flow: the "integration time" is verified if a source of signed time such as an inclusion promise is present, b...