Bump faraday from ~> 1.5 to ~> 2

Updates the basic-auth middleware call to the Faraday 2 form
(`request :authorization, :basic, ...`). Faraday 2.x requires Ruby >=
3.0, so drop Ruby 2.7 from the CI matrix and pin
`required_ruby_version = '>= 3.0'` in the gemspec.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/vmfloaty/http.rb

@@ -37,7 +37,7 @@ class Http
 
     Faraday.new(url: url, ssl: { verify: false }) do |faraday|
       faraday.request :url_encoded
-      faraday.request :basic_auth, user, password
+      faraday.request :authorization, :basic, user, password
       faraday.response :logger if verbose
       faraday.adapter Faraday.default_adapter
     end