fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-THOR-10843853

Gemfile

@@ -2,5 +2,5 @@ source 'https://rubygems.org'
 
 group :development, :test do
   gem 'rake'
-  gem 'vim-flavor', '~> 4.0'
+  gem 'vim-flavor', '~> 4.0', '>= 4.0.3'
 end