add project saver spec and fix

ee/app/models/ee/project.rb

@@ -8,6 +8,7 @@ module EE
 
     prepended do
       include Elastic::ProjectsSearch
+      include Importable
       prepend GeoAwareAvatar
       prepend ImportStatusStateMachine
 
@@ -53,7 +54,7 @@ module EE
       validates :repository_size_limit,
         numericality: { only_integer: true, greater_than_or_equal_to: 0, allow_nil: true }
 
-      validates :approvals_before_merge, numericality: true, allow_blank: true
+      validates :approvals_before_merge, numericality: true, allow_blank: true, unless: :importing?
 
       accepts_nested_attributes_for :remote_mirrors,
         allow_destroy: true,

spec/lib/gitlab/import_export/project_tree_saver_spec.rb

@@ -33,6 +33,10 @@ describe Gitlab::ImportExport::ProjectTreeSaver do
         expect(saved_project_json).to include({ "visibility_level" => 20 })
       end
 
+      it 'has approvals_before_merge set' do
+        expect(saved_project_json['approvals_before_merge']).to eq(1)
+      end
+
       it 'has milestones' do
         expect(saved_project_json['milestones']).not_to be_empty
       end
@@ -241,7 +245,8 @@ describe Gitlab::ImportExport::ProjectTreeSaver do
                      issues: [issue],
                      snippets: [snippet],
                      releases: [release],
-                     group: group
+                     group: group,
+                     approvals_before_merge: 1
                     )
     project.update_column(:description_html, 'description')
     project_label = create(:label, project: project)