Update launchy requirement from ~> 2.4 to ~> 3.0

Updates the requirements on [launchy](https://github.com/copiousfreetime/launchy) to permit the latest version.
- [Changelog](https://github.com/copiousfreetime/launchy/blob/main/README.md)
- [Commits](copiousfreetime/launchy@v2.4.0...v3.0.0)

---
updated-dependencies:
- dependency-name: launchy
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

jekyll-import.gemspec

@@ -63,5 +63,5 @@ Gem::Specification.new do |s|
   end
 
   # site dependencies:
-  s.add_development_dependency("launchy", "~> 2.4")
+  s.add_development_dependency("launchy", "~> 3.0")
 end