build(deps-dev): bump marshmallow from 3.20.2 to 3.21.1

Bumps [marshmallow](https://github.com/marshmallow-code/marshmallow) from 3.20.2 to 3.21.1.
- [Changelog](https://github.com/marshmallow-code/marshmallow/blob/dev/CHANGELOG.rst)
- [Commits](marshmallow-code/marshmallow@3.20.2...3.21.1)

---
updated-dependencies:
- dependency-name: marshmallow
  dependency-type: indirect
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]