Add Logto to Auth

[Rany0101]

Logto is an IAM infrastructure with authentication, authorization, MFA, SSO, user management, and multi-tenancy features. Supports OAuth 2.0, OIDC, and SAML.

Support dedicated Flutter SDK: https://github.com/logto-io/dart (Doc: https://docs.logto.io/quick-starts/flutter)

https://github.com/logto-io

Please read How to contribute before creating a submission.

Description and links to repo and pubdev if any

Submission description/links here

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Checklist

• I read How to contribute
• I edited the SOURCE.md file only
• Added a link to the repo in the PR

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[Solido]

Hi, rule is commercial product can support the repo but it should be official not an entry. Thanks!