Bump Addressable from 2.3.6 to 2.8.0

This version fixes a ReDoS vulnerability in Addressable::Template#match

For more information about the issue:
- https://app.snyk.io/vuln/SNYK-RUBY-ADDRESSABLE-1316242

webmock.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = '>= 2.0'
 
-  s.add_dependency 'addressable', '>= 2.3.6'
+  s.add_dependency 'addressable', '>= 2.8.0'
   s.add_dependency 'crack', '>= 0.3.2'
   s.add_dependency 'hashdiff', ['>= 0.4.0', '< 2.0.0']