Support hyphens in GitLab subdomain regex

To allow Staging Ref env be
configred as gitlab.com instance
Signed-off-by: Nailia Iskhakova <niskhakova@gitlab.com>

lib/gitlab/saas.rb

@@ -18,7 +18,7 @@ module Gitlab
     end
 
     def self.subdomain_regex
-      %r{\Ahttps://[a-z0-9]+\.gitlab\.com\z}.freeze
+      %r{\Ahttps://[a-z0-9-]+\.gitlab\.com\z}.freeze
     end
 
     def self.dev_url

spec/lib/gitlab_spec.rb

@@ -99,6 +99,13 @@ RSpec.describe Gitlab do
       expect(described_class.com?).to eq true
     end
 
+    it 'is true when on other gitlab subdomain with hyphen' do
+      url_with_subdomain = Gitlab::Saas.com_url.gsub('https://', 'https://test-example.')
+      stub_config_setting(url: url_with_subdomain)
+
+      expect(described_class.com?).to eq true
+    end
+
     it 'is false when not on GitLab.com' do
       stub_config_setting(url: 'http://example.com')