chore: restrict webpack versions to latest compatible version

[oliverdietsche]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ x ] The commit message follows our guidelines: link tbd.
• [ x ] Tests for the changes have been added (for bug fixes / features)
• [ x ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ x ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] tooling / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

The latest currently supported webpack version is just below 5. Currently that limitation is not apparent.

Issue Number: #91

What is the new behavior?

The user will get a notice in the terminal when using an incompatible webpack version and it's properly documented on which versions are compatible.

Does this PR introduce a breaking change?

[ ] Yes
[ x ] No

Other information

[ernscht]

cool. thanks a lot. I would merge it immediately, but unfortunately the PerformanceTest fails. We should adjust something there.