fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-REXML-7814166
- https://snyk.io/vuln/SNYK-RUBY-REXML-7577227
- https://snyk.io/vuln/SNYK-RUBY-RACK-1061917
- https://snyk.io/vuln/SNYK-RUBY-REXML-7577228
- https://snyk.io/vuln/SNYK-RUBY-REXML-7462086

Gemfile

@@ -50,7 +50,7 @@ group :development, :test do
   gem 'rspec_junit_formatter'
   gem 'rspec-rails', '~> 6.0.0'
   gem 'rubocop', '~> 1.63', '>= 1.63.0', require: false
-  gem 'rubocop-rails', '~> 2.25', '>= 2.25.1', require: false
+  gem 'rubocop-rails', '~> 2.26', '>= 2.26.0', require: false
 end
 
 group :development do