Bump version and update to .net 6.0

[vkristijan]

Changelist:

• added Id to the Dropzone div
• removed assert for a style class that is no longer in use
• increased the .net version to 6.0, and bumped version to 2.4.0
• updated dependencies
• fixed spacings in unit tests

[vkristijan]

This should be related to Issue #133

[Postlagerkarte]

thx @vkristijan