fix: Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-REXML-12878608

Author: snyk-io[bot]

Gemfile

@@ -18,5 +18,5 @@ end
 group :test do
   gem 'simplecov', '~> 0.22', require: false
   gem 'vcr', '~> 6.3', require: false
-  gem 'webmock', '~> 3.23', require: false
+  gem 'webmock', '~> 3.24', '>= 3.24.0', require: false
 end