Fix uninitialized constant with GitLab Pages deploy

pages:deploy step was failing with the following error:

```
unitialized constant SafeZip::Extract::Zip
```

Since license_finder already pulls in rubyzip, we can make it
a required gem. We also use the scope operator to make the reference to
Zip::File explicit.

Gemfile

@@ -57,7 +57,7 @@ gem 'u2f', '~> 0.2.1'
 # GitLab Pages
 gem 'validates_hostname', '~> 1.0.6'
-gem 'rubyzip', '~> 1.2.2', require: false
+gem 'rubyzip', '~> 1.2.2'
 # Browser detection
 gem 'browser', '~> 2.5'

changelogs/unreleased/sh-fix-pages-zip-constant.yml

+---
+title: Fix uninitialized constant with GitLab Pages
+merge_request:
+author:
+type: fixed

lib/safe_zip/extract.rb

@@ -29,7 +29,7 @@ def extract(opts = {})
     private
     def extract_with_ruby_zip(params)
-      Zip::File.open(archive_path) do |zip_archive|
+      ::Zip::File.open(archive_path) do |zip_archive|
         # Extract all files in the following order:
         # 1. Directories first,
         # 2. Files next,