remove spec expecting german translations

german translations are not part of OpenProject anymore (they are now provided via Crowdin)

spec/models/work_package/work_package_planning_spec.rb

@@ -175,16 +175,9 @@ describe WorkPackage, type: :model do
     end
 
     describe 'parent' do
-      let (:de_message) { 'darf kein Meilenstein sein.' }
-      let (:en_message) { 'cannot be a milestone.' }
-      after(:each) do
-        # proper reset of the locale after the test
-        I18n.locale = 'en'
-      end
+      let (:message) { 'cannot be a milestone.' }
 
       it 'is invalid if parent is_milestone' do
-        ['en', 'de'].each do |locale|
-          I18n.with_locale(locale) do
         parent = WorkPackage.new.tap do |pe|
           pe.send(:assign_attributes, attributes.merge(type: FactoryGirl.build(:type, is_milestone: true)), without_protection: true)
         end
@@ -195,11 +188,7 @@ describe WorkPackage, type: :model do
         expect(planning_element).not_to be_valid
 
         expect(planning_element.errors[:parent_id]).to be_present
-            expect(planning_element.errors[:parent_id]).to eq([send("#{locale}_message")])
-          end
-
-        end
-
+        expect(planning_element.errors[:parent_id]).to eq([message])
       end
     end
   end