Tests can't be built on GHC 9.14

[hasufell]

We can only build tests with a directory older than 1.3.9.0, because otherwise we're getting cycling dependencies.

But 1.3.8.5 doesn't update the base version bounds anymore, it seems.

@Bodigrim

[hasufell]

We'll have to get rid of temporary package in the testsuite. I guess we could also consider adding something like createTempDirectory, similar to openTempFile.