chore(deps): update dependency markdownlint-cli2 to v0.21.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
markdownlint-cli2	0.17.2 → 0.21.0

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Release Notes

DavidAnson/markdownlint-cli2 (markdownlint-cli2)

v0.21.0

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• Refactor options/configuration file loading
• Update dependencies

v0.20.0

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• Update dependencies

v0.19.1

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• Update --format to avoid trailing newline
• Update dependencies

v0.19.0

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• Add --format parameter for editor integration
• Update output formatters for severity warning
• Explicitly version Docker containers for pre-commit
• Update dependencies (including markdownlint)

v0.18.1

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• Update dependencies (including markdownlint)

v0.18.0

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• Use user ID in Docker containers for security
• Update dependencies (including markdownlint)
• Remove support for end-of-life Node 18

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