chore: update dependency to fix security issue

[virkt25]

Description

Updates a 0.x.y dependency. Fixes #1304 (prototype pollution security issue).

Motivation and Context

Downstream projects are getting flagged by Snyk as impacted by the issue.
Fixes #1304

How Has This Been Tested?

deep-extend 0.5.1 was a security fix release as per their changelog.

Screenshots (if appropriate):

Types of changes

• No code changes (changes to documentation, CI, metadata, etc)
• Dependency changes (any modification to dependencies in package.json)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[shockey]

thanks @virkt25!