test: unregister signals when tearDown()

Change-Id: Iab97236dce66a63a660251c495f64154c6db07b7

test/unitTest/call/call.cpp

@@ -121,6 +121,7 @@ CallTest::setUp()
 void
 CallTest::tearDown()
 {
+    DRing::unregisterSignalHandlers();
     JAMI_INFO("Remove created accounts...");
 
     std::map<std::string, std::shared_ptr<DRing::CallbackWrapperBase>> confHandlers;