Upgrade `react-scripts` to version 5.0.0

[ChristophNiehoff]

Currently, we are using react-scripts 4.0.3
This introduces a lot of security warnings

105 vulnerabilities (1 low, 93 moderate, 9 high, 2 critical)

There is a new version of react-scripts available: 5.0.0
This reduces the security warnings to

8 moderate severity vulnerabilities

However, this update introduces problems with jointjs. In particular, some imports are not found anymore.