Fix test cases failing with "ValueError: q must be exactly 160, 224, or 256 bits long"

[Noordsestern]

We have 5 failing test cases all with the same error message:

ValueError: q must be exactly 160, 224, or 256 bits long

We cannot track down anymore how long this error exists, as the logs of workflow executions are not archived by Github. It seems like and outdated encyrption algorithm may be the cause: https://stackoverflow.com/questions/75452354/paramiko-rsakey-private-key-file-is-encrypted

PR #439 might help to solve this.

[Noordsestern]

The issue was that usernames that would not exist has been used: fabric/fabric#2182 (comment)