test: Ensure idempotency in airline creation tests

Added a cleanup step to delete any existing airline before creating a new one in the airlines_spec. This change ensures that the tests are idempotent and do not interfere with each other, improving test reliability.

Author: teetangh

spec/requests/api/v1/airlines_spec.rb

@@ -134,7 +134,11 @@
 
     context 'when the airline is deleted successfully' do
       it 'returns a success message' do
+        # Clean up any existing test data first to ensure idempotent test
+        delete "/api/v1/airlines/#{airline_id}"
+
         post "/api/v1/airlines/#{airline_id}", params: { airline: airline_params }
+        expect(response).to have_http_status(:created)
 
         delete "/api/v1/airlines/#{airline_id}"