fixxing minor rubocop offenses for specs

spec/api/v1/user/financial_transactions_spec.rb

@@ -21,7 +21,7 @@ describe Api::V1::User::FinancialTransactionsController, type: :controller do
     before { request }
 
     it "returns status 200" do
-      expect(response.status).to eq 200
+      expect(response).to have_http_status(:ok)
     end
   end
 

spec/api/v1/user/group_order_articles_spec.rb

@@ -23,7 +23,7 @@ describe Api::V1::User::GroupOrderArticlesController, type: :controller do
     before { request }
 
     it "returns status 200" do
-      expect(response.status).to eq 200
+      expect(response).to have_http_status(:ok)
     end
 
     it "returns the order_article" do

spec/lib/bank_account_information_importer_spec.rb

@@ -4,8 +4,7 @@ describe BankTransaction do
   let(:bank_account) { create :bank_account }
 
   it 'empty content' do
-    content = <<-JSON
-    JSON
+    content = ''
 
     importer = BankAccountInformationImporter.new(bank_account)
     expect(importer.import!(content)).to be_nil