dgitizer mandatory possibility to restrict the input to special characters changed

[astroidex]

Describe the bug
The old way to define a mandatory restriction for the input does not work in digitizer 1.4.x anymore.

old way
mandatory: '/^[0-9]+$/'

New way:

- type: input
  name: mycolumn
  title: Test
  attr: {type: 'number', required: 'required'}
  mandatoryText: 'Only numbers'

https://github.com/mapbender/mapbender-documentation/blob/release/3.2.0/en/functions/editing/digitizer/digitizer_configuration.rst#mandatory-fields

Please update the doku and maybbe check with the developer to get the exact information about the change.