build(deps): update rack requirement from >= 2.1.4, < 2.3.0 to >= 2.1…

….4, < 3.1.0

Updates the requirements on [rack](https://github.com/rack/rack) to permit the latest version.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@2.1.4...3.0.0)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: direct:production
...

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

google_maps_geocoder.gemspec

@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.email = 'rod@foveacentral.com'
   s.signing_key = File.expand_path('~/.ssh/gem-private_key.pem') if $PROGRAM_NAME =~ /gem\z/
 
-  s.add_runtime_dependency 'rack', '>= 2.1.4', '< 2.3.0'
+  s.add_runtime_dependency 'rack', '>= 2.1.4', '< 3.1.0'
 
   s.files = `git ls-files`.split "\n"
   s.require_paths = ['lib']