Update dependency flutter_lints to v6 (main)

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
flutter_lints (source)	dev_dependencies	major	^3.0.0 → 6.0.0

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Release Notes

flutter/packages (flutter_lints)

v6.0.0

Compare Source

v5.0.0

Compare Source

v4.0.0

Compare Source

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Configuration

📅 Schedule: Branch creation - "every 1 hour after 00:00 and before 23:59" in timezone Asia/Tokyo, Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• If you want to rebase/retry this PR, check this box

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: pubspec.lock

Command failed: flutter pub upgrade flutter_lints
pubspec.yaml has no lower-bound SDK constraint.
You should edit pubspec.yaml to contain an SDK constraint:

environment:
  sdk: '^3.11.0'

See https://dart.dev/go/sdk-constraint
Failed to update packages.