Perform the tests on the package that the `tests` attribute is a child
of, i.e. if `discourseAllPlugins.tests` is built, the tests will run
with the `discourseAllPlugins` package, not the `discourse` package as
previously.
(cherry picked from commit 6fd5a40ccaf0b4da1362803a387bf46d381dd66a)
Assert that the PostgreSQL version being deployed is the one used
upstream. Allow the user to override this assertion, since it's not
always possible or preferable to use the recommended one.
(cherry picked from commit 544adbfcab2e92c2fe5774cae67f2edf165eb97e)