Eleventy Image v3.1.0: WebC component, `sharp` upgrade

Full Changelog: v3.0.0...v3.1.0
Milestone: https://github.com/11ty/eleventy-img/milestone/18?closed=1

Release Notes

• Adds <eleventy-image> WebC component, now on the docs: https://www.11ty.dev/docs/plugins/image/#webc
  • Joins the growing list of official Eleventy WebC components: https://www.11ty.dev/docs/languages/webc/#official-webc-components
  • This component requires WebC v0.10.1 or newer.
• Upgrades sharp to v0.32 #178 https://sharp.pixelplumbing.com/changelog#v032---flow
• Update minimal Node requirement in readme. by @solution-loisir in #174