Yesterday, our [Wikibase Secondary CI on GitHub](https://github.com/wikimedia/mediawiki-extensions-Wikibase/actions/workflows/secondaryCI.yml) for changes merged to master broke.
It seems the immediate cause is [phpunit: Deprecate suite.xml and composer phpunit:entrypoint (If2ffe052)](https://gerrit.wikimedia.org/r/c/mediawiki/core/+/937980/) coming from {T227900}.
The [last successful Wikibase Secondary CI run](https://github.com/wikimedia/mediawiki-extensions-Wikibase/actions/runs/7285995071/job/19853902546) had
```
[...]
+ cd ../mediawiki
+ composer phpunit:entrypoint -- --group Wikibase
> phpunit '-c' 'tests/phpunit/suite.xml' '--group' 'Wikibase'
Using PHP 7.4.33
[...]
```
but the [failing ones](https://github.com/wikimedia/mediawiki-extensions-Wikibase/actions/runs/7289631511/job/19864659836) now have
```
[...]
+ cd ../mediawiki
+ composer phpunit:entrypoint -- --group Wikibase
> phpunit '--group' 'Wikibase'
PHPUnit 9.5.28 by Sebastian Bergmann and contributors.
Usage:
phpunit [options] UnitTest.php
phpunit [options] <directory>
Code Coverage Options:
[...]
```
**Acceptance criteria**
* [ ] Wikibase Seconday CI is green again
* [ ] email sending works again, with a somehow more robust solution