rev to 5.0.0 in preparation for publishing

[devoncarew]

• rev to 5.0.0 in preparation for publishing

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• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
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[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:lints	5.0.0	ready to publish	v5.0.0

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.