Version bump to 2.28.3

[mpirri]

Auto-generated by fastlane 🤖

Changes since release '2.28.2':

• Reject internal testers (Reject internal testers #8959) via Mark Pirri
• Removing testers from multiple groups (Removing testers from multiple groups #8957) via Mark Pirri
• showBuildSettings does not require to call clean on Xcode >= 8.3 (showBuildSettings does not require to call clean #8921) via punty
• Check for default external group and support :groups option (Check for default external group and support :groups option #8943) via David Ohayon
• Fix string handling in print_table wrapping (Fix string handling in print_table wrapping #8951) via Michael Furtak
• Put motivation and context above description (Reorder PR template #8953) via Michael Furtak
• Fix deliver preview layout (Fix deliver preview layout #8945) via Fumiya Nakamura
• Add skip_package_ipa option to Gym Sometimes you don’t want an ipa but rather, just the xcarchive. via taquitos

[fastlane-bot]

Hey @mpirri 👋

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 🚀