Update psych requirement from <= 5.1.0 to <= 5.2.0

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@v1.1.0...v5.1.1)

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

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

Gemfile

@@ -7,7 +7,7 @@ gem 'rake'
 gem 'yard'
 gem 'rspec'
 
-gem "psych", '<= 5.1.0'
+gem "psych", '<= 5.2.0'
 
 # Rubocop supports only >=2.2.0
 if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('2.2.0')