RUSTSEC-2023-0071: Please replace rsa by another crate

[sylvestre]

https://rustsec.org/advisories/RUSTSEC-2023-0071.html
it is blocking reqsign to ship in the next Debian release. See:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1057096

[Xuanwo]

Unfortunately, I couldn't find any other crate with better quality to replace rsa. Do you have suggestions?

[Xuanwo]

We only use rsa in google and oracle services, other services not affected.