pin libddwaf version (DataDog#2556)

* pin datadog-ci version

* pin datadog

* quotes

* pin libddwaf

* unpin other libs

Author: amaskara-dd

Gemfile

@@ -9,6 +9,7 @@ group :development, :test do
   gem 'bigdecimal', '= 3.1.9'
   gem 'cucumber', '~> 9.2.1'
   gem 'datadog-ci', '~> 1.11'
+  gem 'libddwaf', '= 1.18.0.0.1'
   gem 'gem-release'
   gem 'rake', '~> 13.0.1'
   gem 'ostruct'