Add cgmanifest file in codeowner list (#13042)
Add cgmanifest file in codeowner list (#13042)

Marks @onnxruntime-admin as owner for cgmanifest file to help review
changes in dependencies and version updates.
microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime