[local_auth] Bump version

[jmagman]

Description

When #2685 was merged the published version was 0.6.1+3 and the pubspec was 0.6.2, so I added appended to the 0.6.2 CHANGELOG. However, local_auth was published on the commit immediately before it and therefore isn't really in 0.6.2.
Bump the version and change the CHANGELOG to reflect this.

Related Issues

#2685

Checklist

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• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See [Contributor Guide]).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (flutter analyze) does not report any problems on my PR.
• I read and followed the [Flutter Style Guide].
• The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I updated pubspec.yaml with an appropriate new version according to the [pub versioning philosophy].
• I updated CHANGELOG.md to add a description of the change.
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Breaking Change

• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.

[jmagman]

Merging for version change on red.