fix: Update and remove GeekMasher from Codeowner

[GeekMasher]

No description provided.

[Copilot]

Pull Request Overview

This PR updates repository ownership and dependency management configuration by transferring ownership from an individual maintainer to a team and adding automated dependency updates.

• Updates CODEOWNERS to transfer ownership from @GeekMasher to @advanced-security/oss-maintainers
• Adds Dependabot configuration for automated GitHub Actions and npm dependency updates

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/CODEOWNERS	Updates ownership from individual maintainer to team
.github/dependabot.yml	Adds automated dependency update configuration

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