account creation fails with umlaut (diacritic) in security token

[Reise-Reise]

tested with Docker image passbolt/passbolt:3.7.3-1-ce and passbolt/passbolt:3.8.1-1-ce

steps to reproduce:

1. create a new user
2. set passphrase
3. save key file
4. for the security token:
   • pick any color
   • input 3 charcaters withe at least one Umlaut (äöüÄÖÜß)

results in the error message:

Could not validate entity Account.

{
    "security_token": {
        "required": "The security_token is required."
    }
}