The reference to 3.1.8 (in fact to any 3rd party version) is not a binding one. As stated it's a reference to the version with which tests were done some (long) time ago. You should be able to use newer versions (as indeed you have done).
If there is some problem in our support of a newer version (as opposed to a bug in that version's implementation), please provide a concrete example (Tersus project), and we'll surely have a look at it.
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