As can be seen in https://integration.wikimedia.org/ci/job/wmf-quibble-core-vendor-mysql-php72-docker/9691/console :
```
PHP Fatal error: Declaration of Cache\IntegrationTests\SimpleCacheTest::setUp() must be compatible with PHPUnit\Framework\TestCase::setUp(): void in /workspace/src/vendor/cache/integration-tests/src/SimpleCacheTest.php on line 713
```
Upstream bug: https://github.com/php-cache/integration-tests/issues/99
[[ https://github.com/php-cache/integration-tests/commit/ba6fcfd823d623ba73c2faba5a208067281c4c38 | The fix ]] appears to be in master, but not released.
>>! In T237164#5896034, @Addshore wrote:
> So to move forward this would have to be re added, pinned at the specific version too.
>
> And then this starts becoming messier, as outlined in T199440 this is not an ideal situation but apparently the only way we could make it work with the WMF CI.
> I'd propose we also restore this require-dev in the core composer.json for now pinned to the same version as in Wikibase, essentially restoring the way things were.