Code doesnt work for chain.pem #161

Hi, thanks for working on this great library. I am running into an issue signing the certificate using KMS key and have a chain.pem which was working fine in c2pa-python 0.5 but for the 0.20.0, the code gives following error.

Traceback (most recent call last):
File "C:\Users\shaya\Desktop\c2pa-python\examples\final_c2pa_020.py", line 137, in
extend_manifest(source_file, signed_file, signer, new_manifest)
File "C:\Users\shaya\Desktop\c2pa-python\examples\final_c2pa_020.py", line 74, in extend_manifest
builder.sign_file(
File "C:\Users\shaya\anaconda3\envs\python-c2pa-0.20\lib\site-packages\c2pa\c2pa.py", line 2591, in sign_file
raise C2paError(f"Error signing file: {str(e)}") from e
c2pa.c2pa.C2paError: Error signing file: Signature: the signature does not match the provided data or public key

However, if i use the standalone certificate instead of the chain.pem, then it works fine. But thats not what we want. Is this a known issue ? Or any way i can resolve this ?