Could not find gem 'another-jekyll-plugin x64-mingw32' in any of the gem sources – SEO

I am trying to use jekyll on windows however when I run

bundle exec jekyll serve

I get an error saying

Could not find gem ‘rspec (~> 3.4) x64-mingw32’ in any of the gem
sources listed in your Gemfile or in gems cached in vendor/cache. Run
bundle install to install missing gems.

Then when I run bundle install I get

Could not find gem ‘another-jekyll-plugin x64-mingw32’ in any of the
gem sources listed in your Gemfile or in gems cached in vendor/cache.

here is the bundle env

Environment

Bundler       2.0.2
  Platforms   ruby, x64-mingw32
Ruby          2.5.5p157 (2019-03-15 revision 67260) [x64-mingw32]
  Full Path   D:/Ruby25-x64/bin/ruby.exe
  Config Dir  C:/ProgramData
RubyGems      2.7.6.2
  Gem Home    D:/Ruby25-x64/lib/ruby/gems/2.5.0
  Gem Path    C:/Users/austi/.gem/ruby/2.5.0;D:/Ruby25-x64/lib/ruby/gems/2.5.0
  User Path   C:/Users/austi/.gem/ruby/2.5.0
  Bin Dir     D:/Ruby25-x64/bin
Tools
  Git         2.22.0.windows.1
  RVM         not installed
  rbenv       not installed
  chruby      not installed

Bundler Build Metadata

Built At          2019-06-13
Git SHA           496bca538
Released Version  true

Gemfile

Gemfile

source 'https://rubygems.org'

# Specify your gem's dependencies in jekyll-admin.gemspec
gemspec

# Site dependencies
gem 'jekyll-seo-tag'
gem 'jekyll-sitemap'
gem 'rake', '12.3.1'
group :jekyll_plugins do
    gem "jekyll-gist"
    gem "jekyll-coffeescript"
    gem "jekyll-assets"
    gem "another-jekyll-plugin"
  end

Gemfile.lock

<No D:/anautics/jekyll-admin/Gemfile.lock found>

Gemspecs

jekyll-admin.gemspec

# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'jekyll-admin/version'

Gem::Specification.new do |spec|
  spec.name          = "jekyll-admin"
  spec.version       = JekyllAdmin::VERSION
  spec.authors       = ["Mert Kahyaoğlu", "GitHub Open Source"]
  spec.email         = ["[email protected]", "[email protected]"]

  spec.summary       = %q{wp-admin for Jekyll, but better}
  spec.description   = %q{Jekyll::Admin is a drop in administrative framework for Jekyll sites.}
  spec.homepage      = "https://github.com/jekyll/jekyll-admin"
  spec.license       = "MIT"

  # Prevent pushing this gem to RubyGems.org. To allow pushes either set the 'allowed_push_host'
  # to allow pushing to a single host or delete this section to allow pushing to any host.
  if spec.respond_to?(:metadata)
    spec.metadata['allowed_push_host'] = "https://rubygems.org"
  else
    raise "RubyGems 2.0 or newer is required to protect against public gem pushes."
  end

  spec.files         = Dir.glob("lib/**/*").concat(%w(LICENSE README.md))
  spec.bindir        = "exe"
  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
  spec.require_paths = ["lib"]

  spec.add_dependency "jekyll", "~> 3.3"
  spec.add_dependency "sinatra", "~> 1.4"
  spec.add_dependency "sinatra-contrib", "~> 1.4"
  spec.add_dependency "addressable", "~> 2.4"

  spec.add_development_dependency "bundler", "~> 1.7"
  spec.add_development_dependency "rake", "~> 10.0"
  spec.add_development_dependency "rspec", "~> 3.4"
  spec.add_development_dependency "rubocop", "~> 0.57.2"
  spec.add_development_dependency "sinatra-cross_origin", "~> 0.3"
  spec.add_development_dependency "gem-release", "~> 0.7"
end