chore(gemfile+lock): pin versions of key dependencies

* use versions in line with Chef Workstation v25.2.1075

Author: dafyddj

Gemfile

@@ -15,8 +15,10 @@ gem 'inspec', git: 'https://gitlab.com/saltstack-formulas/infrastructure/inspec'
 gem 'kitchen-docker', git: 'https://gitlab.com/saltstack-formulas/infrastructure/kitchen-docker', branch: 'ssf'
 # rubocop:enable Layout/LineLength
 
-gem 'kitchen-inspec', '>= 2.5.0'
-gem 'kitchen-salt', '>= 0.7.2'
+gem 'kitchen-inspec', '2.6.2'
+gem 'kitchen-salt', '0.7.2'
 
 # Avoid the error 'pkeys are immutable on OpenSSL 3.0'
 gem 'net-ssh', '>= 7.0.0'
+
+gem 'test-kitchen', '3.6.0'