Bump marshmallow from 3.20.1 to 3.26.2

Bumps [marshmallow](https://github.com/marshmallow-code/marshmallow) from 3.20.1 to 3.26.2.
- [Changelog](https://github.com/marshmallow-code/marshmallow/blob/dev/CHANGELOG.rst)
- [Commits](marshmallow-code/marshmallow@3.20.1...3.26.2)

---
updated-dependencies:
- dependency-name: marshmallow
  dependency-version: 3.26.2
  dependency-type: indirect
...

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Author: dependabot[bot]