Getting an error when i try to in cert_tools repo

when i run “instantiate-certificate-batch -c conf.ini” in the cert_tools repository iam getting this error
raceback (most recent call last):
File “/home/jose/.local/bin/instantiate-certificate-batch”, line 8, in
File “/home/jose/.local/lib/python3.10/site-packages/cert_tools/”, line 131, in main
File “/home/jose/.local/lib/python3.10/site-packages/cert_tools/”, line 97, in instantiate_batch
certs = create_unsigned_certificates_from_roster(template, recipients, use_identities, config.additional_per_recipient_fields)
File “/home/jose/.local/lib/python3.10/site-packages/cert_tools/”, line 56, in create_unsigned_certificates_from_roster
issued_on = helpers.create_iso8601_tz()
File “/home/jose/.local/lib/python3.10/site-packages/cert_tools/”, line 61, in create_iso8601_tz
return ret.isoformat()
AttributeError: ‘str’ object has no attribute ‘isoformat’. Did you mean: ‘format’?
what could be the problem?

cert_tools has received very little attention in the past years and may not be the most reliable library offered by blockcerts.

As it seems, there is a python error where the type of the value does not have the isoformat method (since it seems it is a string).