npm test polutes log with many errors

[blcham]

See example log here:
https://github.com/kbss-cvut/s-forms/actions/runs/5534301619/jobs/10099066069?pr=220

Example errors:

[VojtechLunak]

@blcham Might be duplicate of #176

[LaChope]

To resolve this logs:

From react documentation, a component must be prepared for assertion using act(). It is usually already integrated in React-testing librabry, but in case of asynchronous updates, it must be wrapped in waitFor(). See #229.