Error on creating new cards in card group

# Bug Report

## Prerequisites

* [ not tested ] Can you reproduce the problem on TYPO3 v8.7 LTS
* [ no ] Can you reproduce the problem on TYPO3 v9.5 LTS
* [ yes ] Did you [perform a cursory search](https://github.com/issues?q=is%3Aissue+user%3Abenjaminkott+repo%3Abenjaminkott%2Fbootstrap_package)
to see if your bug or enhancement is already reported?

## Description

With Typo3 v10.4.6 and Bootstrap Package v11.0.2, "Error undefined" is displayed in the backend, if one tries to add a new card to a card group using the [+]-Button ("Create new record after this record") on an existing card element.
The detailed error message in the log is as follows:

`Core: Exception handler (WEB): Uncaught TYPO3 Exception: #1444434102: An inlineChildChildUid is given for table tx_bootstrappackage_card_group_item, but no foreign_selector in inlineParentConfig | UnexpectedValueException thrown in file /var/www/typo3_src-10.4.6/typo3/sysext/backend/Classes/Form/FormDataProvider/DatabaseRowInitializeNew.php in line 170. Requested URL: http://127.0.0.1/typo3/index.php?route=%%2Fajax%%2Frecord%%2Finline%%2Fcreate&token=--AnonymizedToken--`

## Steps to Reproduce

1. Create Card Group and add two cards using the [+ Create new] Button above the card elements.
2. Try to add a new card by pressing the [+] Button on the first card created.

### Expected behavior

A new card is created.

### Actual behavior

A red dialog staiting "Error undefined" is displayed at the top right. No new card is created.

## Versions
Typo3 v10.4.6
Bootstrap Package v11.0.2