Final v3.x release with compatible improvements from v4.0.0

What's Changed

• Add default fallthrough cases by @wravery in #166
• Add a learn_star_wars sample based on https://graphql.org/learn/ by @wravery in #168
• Backport compatible changes from v4.0.0 to v3.7.0 by @wravery in #190

Full Changelog: v3.6.0...v3.7.0