PhpunitVersionDependentTestCompatibilityTrait has different cases

Problem/Motivation

In PhpUnitCompatibilityTrait.php there is a comparison that takes place that can never be true because the letter u of Unit is lowercase in one place and upper case in another. As linux is case sensitive the trait will always be re-created. Marking as minor because it doesn't break anything.

if (!trait_exists(PhpunitVersionDependentTestCompatibilityTrait::class, FALSE)) {
  class_alias("Drupal\TestTools\PhpUnitCompatibility\PhpUnit" . RunnerVersion::getMajor() . "\TestCompatibilityTrait", PhpUnitVersionDependentTestCompatibilityTrait::class);
}

Steps to reproduce

N/A

Proposed resolution

Make the cases match.

Remaining tasks

User interface changes

N/A

API changes

N/A

Data model changes

N/A

Release notes snippet