chore(deps): update fetch-mock and node-fetch to latest versions

[subhankarmaiti]

This PR removes outdated polyfills and legacy dependencies to address security vulnerabilities and improve long-term maintainability.

Key Changes

• Removed:

  • core-js@2.x

• Upgraded:

  • fetch-mock from ^7.7.3 → ^12.5.3
  • node-fetch from ^2.7.0 → ^3.3.2

Why This Change?

• Security Compliance:
  core-js@2 and babel-polyfill are deprecated and have known vulnerabilities.

Impact

• No runtime functionality is affected.
• This cleanup mainly targets dev and test dependencies.

Testing

• ✅ All CI checks are passing.
• ✅ Ran unit tests locally—no regressions found.
• ✅ Verified local functionality manually to ensure no runtime impact.