Only create Versions DF when needed

spec/lib/db/dynamic_finders/plugin_spec.rb

@@ -46,6 +46,17 @@ describe WPScan::DB::DynamicFinders::Plugin do
 
   describe '.create_versions_finders' do
     # handled and tested in spec/lib/finders/dynamic_finders/plugin_version_spec
+
+    describe 'Try to create the finders twice' do
+      # let's just test one slug, no need to test them all
+      let(:slug) { '12-step-meeting-list' }
+
+      it 'does not raise an error when the class already exists' do
+        WPScan::DB::DynamicFinders::Plugin.create_versions_finders(slug)
+
+        expect { WPScan::DB::DynamicFinders::Plugin.create_versions_finders(slug) }.to_not raise_error
+      end
+    end
   end
 
   describe '.version_finder_super_class' do