Update dependency marshmallow to v4

This MR contains the following updates:

Package	Change	Age	Confidence
marshmallow (changelog)	==3.26.1 -> ==4.0.0

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This MR has been generated by Renovate Bot.

mentioned in issue #40

added 7 commits

• 2a66f458...b7acad3f - 6 commits from branch master
• dbd142cc - Update dependency marshmallow to v4

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