Require ruby >=3.0

Although we don't technically require it, we should match what smart-proxy
itself needs to prevent issues in CI.

Author: adamruzicka

smart_proxy_remote_execution_ssh.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |gem|
   gem.require_paths    = ["lib"]
   gem.license = 'GPL-3.0-only'
 
-  gem.required_ruby_version = '>= 2.7.0'
+  gem.required_ruby_version = '>= 3.0'
 
   gem.add_development_dependency("rake", '~> 13.0')
   gem.add_development_dependency('minitest', '~> 5.23')