Add Ruby 4.0 support

Bumps [voxpupuli/ruby-version](https://github.com/voxpupuli/ruby-version) from 1 to 2.
- [Release notes](https://github.com/voxpupuli/ruby-version/releases)
- [Commits](voxpupuli/ruby-version@v1...v2)

---
updated-dependencies:
- dependency-name: voxpupuli/ruby-version
  dependency-version: '2'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/ruby.yml

@@ -23,7 +23,7 @@ jobs:
         ruby-version: '3.4'
         bundler-cache: true
     - id: ruby
-      uses: voxpupuli/ruby-version@v1
+      uses: voxpupuli/ruby-version@v2
 
   test:
     runs-on: ubuntu-24.04

vanagon.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |gem|
   gem.authors  = ['Puppet By Perforce', 'OpenVoxProject']
   gem.email    = 'voxpupuli@groups.io'
   gem.homepage = 'http://github.com/OpenVoxProject/vanagon'
-  gem.required_ruby_version = ['>= 3.2', '< 4']
+  gem.required_ruby_version = ['>= 3.2', '< 5']
 
   gem.add_dependency('docopt', '~> 0.6.1')
   # Handle git repos responsibly
@@ -31,6 +31,8 @@ Gem::Specification.new do |gem|
   gem.add_dependency('packaging', '~> 0.122.3')
   gem.add_dependency('psych', '>= 4.0', '< 6')
 
+  gem.add_dependency('ostruct', '< 0.7')
+
   gem.require_path = 'lib'
   gem.bindir       = 'bin'
   gem.executables  = %w[vanagon build inspect ship render repo sign