Is your feature request related to a problem? Please describe.
Currently the generated passphrase word separator can be set to a static value. Some other password managers allow using random numbers as the word separator. This can add a bit more entropy while still retaining the easy-to-type/remember property of passphrases.

Describe the solution you'd like
When generating a passphrase, expose a choice between a static word separator and "random numbers" as the word separator.

Describe alternatives you've considered
N/A

Additional context
N/A