GHSA-P433-9WV8-28XJ ONNX: External Data Symlink Traversal

Summary - Issue: Symlink traversal in external data loading allows reading files outside the model directory. - Affected code: onnx/onnx/checker.cc: resolveexternaldatalocation used via Python onnx.externaldatahelper.loadexternaldataformodel. - Impact: Arbitrary file read confidentiality breach...