fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-OMNIAUTHSAML-7930878
- https://snyk.io/vuln/SNYK-RUBY-RUBYSAML-7926869
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-3164751

Gemfile

@@ -39,7 +39,7 @@ end
 
 gem 'net-ldap', '~> 0.17'
 gem 'omniauth-cas', '~> 2.0'
-gem 'omniauth-saml', '~> 1.10'
+gem 'omniauth-saml', '~> 2.2', '>= 2.2.0'
 gem 'gitlab-omniauth-openid-connect', '~>0.10.0', require: 'omniauth_openid_connect'
 gem 'omniauth', '~> 1.9'
 gem 'omniauth-rails_csrf_protection', '~> 0.1'