fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-ACTIONPACK-6274386
- https://snyk.io/vuln/SNYK-RUBY-ACTIONPACK-6274388
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-6228056
- https://snyk.io/vuln/SNYK-RUBY-RACK-6274383
- https://snyk.io/vuln/SNYK-RUBY-RACK-6274384
- https://snyk.io/vuln/SNYK-RUBY-RACK-6274385

Gemfile

@@ -7,7 +7,7 @@ ruby '2.6.3'
 # gem 'easymon', '1.2.2'
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-gem 'rails', '~> 5.2.3'
+gem 'rails', '~> 7.0.8', '>= 7.0.8.1'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server