Simplify the gem package file filter in the gemspec template

[orien]

What was the end-user or developer problem that led to this PR?

When using bundle gem to create a new project, the generated gemspec uses a complex regular expression in the gem package file filter. This complexity will impede many developers if they need to make adjustments here.

What is your fix for the problem, implemented in this PR?

I propose to replace the regular expression with simple string comparisons. I think this will be much more approachable for many developers.

Example of a generated gemspec:

  spec.files = Dir.chdir(__dir__) do
    `git ls-files -z`.split("\x0").reject do |f|
      f.start_with?(*%w[my_project.gemspec bin test spec features .git .circleci appveyor])
    end
  end

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

[welcome]

Thanks for opening a pull request and helping make RubyGems and Bundler better! Someone from the RubyGems team will take a look at your pull request shortly and leave any feedback. Please make sure that your pull request has tests for any changes or added functionality.

We use GitHub Actions to test and make sure your change works functionally and uses acceptable conventions, you can review the current progress of GitHub Actions in the PR status window below.

If you have any questions or concerns that you wish to ask, feel free to leave a comment in this PR or join our #rubygems or #bundler channel on Slack.

For more information about contributing to the RubyGems project feel free to review our CONTRIBUTING guide

[deivid-rodriguez]

Makes sense to me!

[deivid-rodriguez]

Merging since there was no further feedback and I like this.