Bump marshmallow from 2.18.0 to 3.7.1

Bumps marshmallow from 2.18.0 to 3.7.1.

Changelog

Sourced from marshmallow's changelog.

3.7.1 (2020-07-20)

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Bug fixes:

• fields.Boolean correctly serializes non-hashable types (🇵🇷1633). Thanks :user:jun0jang for the PR.

3.7.0 (2020-07-08)

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Deprecations:

• marshmallow.pprint is deprecated and will be removed in marshmallow 4 (:issue:1588).

Support:

• Document default_error_messages on field classes (🇵🇷1619). Thanks :user:weeix.

Bug fixes:

• Fix passing only and exclude to Nested with an ordered Schema (🇵🇷1627). Thanks :user:juannorris for the PR.

3.6.1 (2020-06-02)

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No code changes--only docs and contributor-facing updates in this release.

Support:

• Documentation: improve custom fields example (:issue:1538). Thanks :user:pablospizzamiglio for reporting the problem with the old example and thanks :user:Resinderate for the PR.
• Documentation: Split up API reference into multiple pages and add summary tables (🇵🇷1587). Thanks :user:EpicWink for the PR.

3.6.0 (2020-05-08)

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Features:

• Add validators.ContainsNoneOf (:issue:1528). Thanks :user:Resinderate for the suggestion and the PR.

3.5.2 (2020-04-30)

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Bug fixes:

... (truncated)

Commits

• 63670fb Bump version and update changelog
• f6f468d Update AUTHORS and CHANGELOG
• 1ab5cf7 Fix boolean handle unhashable exception
• 09c5b26 Bump version and update changelog
• ca4512c Bump mypy from 0.780 to 0.781 and pre-commit autoupdate (#1618)
• 08c4d36 Fix usage of intersection/union for OrderedSet in Nested field (#1627)
• 2ca48bf Bump sphinx from 3.1.1 to 3.1.2
• 6445050 Update nested param documentation
• f786b14 Fix docs inconsistency (#1624)
• cee3e4e Include default_error_messages for field classes (#1619)
• Additional commits viewable in compare view