Merge changes from 9.0-stable into master (please don't squash commits)

[johnnyshields]

Please merge without squashing commits, so that we can track the two branches are sync'ed-up.

[alcaeus]

@johnnyshields the Ruby team generally doesn't merge up their branches, but cherry-picks to older branches. Can you elaborate on what the reason is for merging 9.0 into master?

[johnnyshields]

Merging changes done on x.y-stable branches back into master would be an excellent practice for the MongoDB Ruby team to adopt. Not only does it act as a check-sum to ensure the team hasn't missed any critical commits/fixes done on those branches--this has happened in the past for Mongoid!--it also makes it much easier for external users like myself to understand what has changed when upgrading.

Git was made to make branch management easy. Let's use it! 💪

[Copilot]

Pull Request Overview

This PR merges changes from the 9.0-stable branch into master, including version updates and Rails compatibility fixes. The changes focus on maintaining compatibility with older Rails versions and updating the library version.

• Update Mongoid version from 9.0.2 to 9.0.6
• Add Rails version check to skip app tests for Rails < 7.1
• Pin concurrent-ruby dependency to version < 1.3.5 for Rails 6.1 compatibility

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/mongoid/version.rb	Updates Mongoid version to 9.0.6
spec/integration/app_spec.rb	Adds Rails version check to skip tests for older Rails versions
gemfiles/rails-6.1.gemfile	Pins concurrent-ruby dependency for compatibility

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