#86: Remove deprecated helmet.featurePolicy call

[paulshryock]

Summary

helmet.featurePolicy() is deprecated as of 3.23.0. This call has been removed, and the Feature Policy HTTP header is now set by the feature-policy module.

Issues

Closes #86

Changelog

Added

• Install feature-policy module.

Removed

• Remove deprecated helmet.featurePolicy() call.

Fixed

• Set Feature Policy HTTP header by feature-policy module.

Checklist

• [ ] I have tested this code
• [x] I have updated the Changelog
• [ ] I have updated the Docs
• [ ] I have updated the Readme