Update jekyll-feed requirement from 0.12.1 to 0.13.0
Update jekyll-feed requirement from 0.12.1 to 0.13.0

Updates the requirements on [jekyll-feed](https://github.com/jekyll/jekyll-feed) to permit the latest version.
- [Release notes](https://github.com/jekyll/jekyll-feed/releases)
- [Changelog](https://github.com/jekyll/jekyll-feed/blob/master/History.markdown)
- [Commits](https://github.com/jekyll/jekyll-feed/compare/v0.12.1...v0.13.0)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
ferrarimarco/personal-website,ferrarimarco/personal-website,ferrarimarco/personal-website,ferrarimarco/personal-website