stop using deprecated jose abstractclassmethod (#9045)
stop using deprecated jose abstractclassmethod (#9045)

The josepy 1.10.0 release deprecated this decorator and [caused the nightly `nopin` test to break](https://dev.azure.com/certbot/certbot/_build/results?buildId=4548&view=logs&j=ce03f7c1-1e3f-5d55-28be-f084e7c62a50&t=597fea95-d44e-53a2-5b71-76ed20bd4dde).
letsencrypt/letsencrypt,lmcro/letsencrypt,letsencrypt/letsencrypt,lmcro/letsencrypt