Fix jboss-seam compile scope dependency on testng

from Julien Carsique:

Drive tests failed because of the execution of the TestNG provider, caused by the use of nuxeo-platform-webapp-base in test scope.
Here's the generic fix for the whole Nuxeo platform: NXP-15167 - Force JUnit 4 provider for Surefire

However, in that case, the issue came from jboss-seam which has a compile scope dependency on testng instead of test scope.

org.nuxeo.ecm.platform:nuxeo-platform-webapp-base:jar:5.9.6-SNAPSHOT
+- org.jboss.seam:jboss-seam:jar:2.3.1.Final.NX01-SNAPSHOT:compile

Can you fix that wrong scope or is it really needed at compile scope?