Update psych requirement from ~> 3.1 to >= 3.1, < 5.0

Updates the requirements on [psych](https://github.com/ruby/psych) to permit the latest version.
- [Release notes](https://github.com/ruby/psych/releases)
- [Commits](ruby/psych@v3.1.0...v4.0.0)

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

reek.gemspec

@@ -32,6 +32,6 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'kwalify', '~> 0.7.0'
   s.add_runtime_dependency 'parser',  '~> 3.0.0'
-  s.add_runtime_dependency 'psych',   '~> 3.1'
+  s.add_runtime_dependency 'psych',   '>= 3.1', '< 5.0'
   s.add_runtime_dependency 'rainbow', '>= 2.0', '< 4.0'
 end