[fastlane] drop Ruby 2.0, 2.1, 2.2 and 2.3 from gemspec

[Kaspik]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary - Supported versions are not mentioned anywhere or I didn't find the place.

Motivation and Context

Circle.ci officially stopped supporting Ruby 2.3, we have no test coverage for that and they all are at EOL. There is no reason to keep supporting this without being sure it works via tests.

[Kaspik]

@joshdholtz Found annoying bug here - Execute tests on Ubuntu was using old Docker image fastlane/ci:0.1.0 with Ruby 2.3.4 instead of 2.4.5...

Let me know if you are okay with this PR for drop, or if not then what do you think. 😊

[joshdholtz]

@Kaspik Good call on bumping up that docker image version 👌 Looks like Ubuntu tests are failing due to not being able to unzip an IPA in verify_build. You want to look into or want me to look into?

[Kaspik]

I wonder if it has something to do with the new docker file, otherwise there was no change. It uses system unzip, right? - unzip #{build_path.shellescape} -d #{dir.shellescape} -x '__MACOSX/*' '*.DS_Store'

Honestly I have no idea how to debug this.

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[joshdholtz]

@Kaspik I ended up reruning the CircleCI build with an SSH session. I was then able to run the exact unzip command that it was failing in on got this. I’m going to fix by trying to unzip a different incorrectly signed IPA that won’t zip bomb

circleci@2c6ee3bb767d:~/project$ unzip fastlane_core/spec/fixtures/ipas/ContainsWatchApp.ipa -d /tmp/123 -x '__MA
COSX/*' '*.DS_Store'
Archive:  fastlane_core/spec/fixtures/ipas/ContainsWatchApp.ipa
  inflating: /tmp/123/ContainsWatchApp/Payload/Sample.app/Watch/Sample WatchKit App.app/Info.plist  
error: invalid zip file with overlapped components (possible zip bomb)

[joshdholtz]

@googlebot I consent.

[googlebot]

CLAs look good, thanks!

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[Kaspik]

Wohou, nice! Thanks for this, if all good now, oky to merge from my side. :)

[joshdholtz]

@Kaspik Looks like its good! I’ll wait for the other tests to pass. Also... TIL about zip bombs lol. I had no idea that was a thing.

[Kaspik]

Yeah that’s an interesting one. 😂

[joshdholtz]

We’re good now! Let’s drop these 💪

[fastlane-bot]

Hey @Kaspik 👋

Thank you for your contribution to fastlane and congrats on getting this pull request merged 🎉
The code change now lives in the master branch, however it wasn't released to RubyGems yet.
We usually ship about once a week, and your PR will be included in the next one.

Please let us know if this change requires an immediate release by adding a comment here 👍
We'll notify you once we shipped a new release with your changes 🚀

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.147.0 🚀