Prerelease: Eleventy Image v6.0.0-beta.4

Probably the last beta before v6.0.0 stable.

• Upgrades to @11ty/eleventy-fetch to v5.0.2 #262
• Breaking: upgrades @11ty/eleventy-utils from v1 to v2.0.0 requires Node 18+ #270
• Breaking: upgrades entities from v5 to v6.0.0, release notes: https://github.com/fb55/entities/releases/tag/v6.0.0

Full v6 Milestone: https://github.com/11ty/eleventy-img/milestone/22?closed=1
Full Changelog: v6.0.0-beta.3...v6.0.0-beta.4