Don't let toast elapse in background in some browsers

[knollengewaechs]

URL of deployed dev instance (used for testing):

• https://timeouttabnotinbackground.webknossos.xyz/

Steps to test:

• Use Chrome or sth. Chromium based
• Do anything that takes a bit of time and where toasts are shown in the process, such as: - upload a larger dataset and switch the tab - wait until the upload is done for a while - go back to the WK tab and make sure both toasts are shown at least for a very short time (there should be at least two toasts after switching back)
• create scenarios where error toasts and warning toasts are shown. Make sure that their content is printed to the console, except if the toast content is a more complex react node (containing a link, for example).

Issues:

• fixes #4719

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• [x] Updated changelog