* chore(testing): run flarum/testing packages tests back again
These tests were not run on each framework build, I enabled them again.
Two of the tests were failing so I disabled them for now, it is more
important to have some tests running than none at all.
* chore(testing): remove flarum/testing dedicated workflow
It is useless now that the tests are run in the framework repo.
Also this workflow was not working anymore.
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Co-authored-by: Sami Mazouz <sychocouldy@gmail.com>
Since we're making changes for the dev version of core, we should test against that too.
For now, this fixes issues with the `extensions` method of `Installation` being undefined.
