devel/pyotherside-qt5: Add missing qt5-declarative-test dependency.

It fixes the following error:
Project ERROR: Unknown module(s) in QT: qmltest

Approved by:	portmgr (build fix blanket)

devel/pyotherside-qt5/Makefile

@@ -11,8 +11,8 @@ LICENSE=	ISCL
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 USES=		compiler:c++11-lang gettext-runtime gl python:3.4+ qmake qt:5
-USE_QT=		core declarative gui network quickcontrols svg testlib \
-		widgets buildtools_build
+USE_QT=		core declarative declarative-test gui network quickcontrols \
+		svg testlib widgets buildtools_build
 USE_GL=		gl
 
 USE_GITHUB=	yes