[action] deprecate the ensure_xcode_version action

[revolter]

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 see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

I saw that this action also depends on the xcode-install gem:

fastlane/fastlane/lib/fastlane/actions/ensure_xcode_version.rb

Line 5 in 4ac1d96

Actions.verify_gem!('xcode-install')

similar to xcversion:

fastlane/fastlane/lib/fastlane/actions/xcversion.rb

Line 5 in 4ac1d96

Actions.verify_gem!('xcode-install')

so it should be deprecated as well.

Description

Testing Steps

[rogerluan]

Sorry I'm late to reviewing this PR, I wasn't aware of it 😬 I just saw it in the release notes of fastlane. There was a reason this action wasn't deprecated before, and it's explained in the migration guide: https://github.com/xcpretty/xcode-install/blob/master/MIGRATION.md#3-ensure_xcode_version

Long story short, depending on how you use ensure_xcode_version, it may not be possible to migrate to xcodes.

Do we still want to keep this action marked as deprecated? 🤔 @revolter @getaaron

[revolter]

Oh, I didn't know 😱

I can revert this, and instead, only add a short bit in the description stating that it's deprecated if you use strict: true.

[revolter]

Or, to push things forward instead, if no one complained, maybe the majority already migrated and/or are not using (anymore) strict: false 🤔

Otherwise, we force ourselves to keep this sort of deprecated action for a longer time.

[rogerluan]

if no one complained

The release went out only a few hours ago, and it's a friday night/saturday 😅

But my gut feeling is that not a lot of people use this action with strict: false anyway 🤷 but this shouldn't be our MO regardless, I think...