dropdown not working in bootstaps 3.1.1 rails 6.0.2.1

bootstaps is working but dropdown not working

yarn add jquery@3.1.1 bootstrap@3.1.1 same version used for both is there any other gem need to install? i tried multiple bootstaps dropdowns in cutom.scss I only used bootstraps is it okay? because bootstrap-sprockets giving me error

custom.scss

@import "bootstrap";

environment.js

// const { environment } = require('@rails/webpacker')
//  const webpack = require('webpack')
//      environment.plugins.prepend('Provide',
//      new webpack.ProvidePlugin({
//      $: 'jquery/src/jquery',
//      jQuery: 'jquery/src/jquery'
//  })
// )
// module.exports = environment

const { environment } = require('@rails/webpacker')
const webpack = require("webpack")
environment.plugins.append("Provide", new webpack.ProvidePlugin({
$: 'jquery',
jQuery: 'jquery',
Popper: ['popper.js', 'default']
}))
module.exports = environment

application.js

// This file is automatically compiled by Webpack, along with any other files
// present in this directory. You're encouraged to place your actual application logic in
// a relevant structure within app/javascript and only use these pack files to reference
// that code so it'll be compiled.

require("@rails/ujs").start()
require("turbolinks").start()
require("@rails/activestorage").start()
require("channels")
require("jquery")
import "bootstrap"


require("bootstrap/dist/js/bootstrap")

// Uncomment to copy all static images under ../images to the output folder and reference
// them with the image_pack_tag helper in views (e.g <%= image_pack_tag 'rails.png' %>)
// or the `imagePath` JavaScript helper below.
//
// const images = require.context('../images', true)
// const imagePath = (name) => images(name, true)

gemfile

    source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby '2.7.0'

gem 'rails', '~> 6.0.2', '>= 6.0.2.1'
gem 'sqlite3', '~> 1.4'
gem 'puma', '~> 4.1'
gem 'sass-rails', '5.1.0'
gem 'webpacker', '~> 4.0'
gem 'turbolinks', '~> 5'
gem 'jbuilder', '~> 2.7'
gem 'bootsnap', '>= 1.4.2', require: false

 gem 'bcrypt', '3.1.13'
gem 'bootstrap-sass', '3.1.1'

group :development, :test do
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '>= 3.0.5', '< 3.2'
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
end

group :test do
  gem 'capybara', '>= 2.15'
  gem 'selenium-webdriver'
  gem 'webdrivers'
end


gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]