dev-games/newton: Remove unnecessary use of unpacker

Replace the unnecessary use of unpacker.eclass with built-in EAPI
unpacking.

Closes: gentoo#8290

dev-games/newton/newton-3.13.ebuild

@@ -1,8 +1,8 @@
-# Copyright 1999-2016 Gentoo Foundation
+# Copyright 1999-2018 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=5
-inherit eutils toolchain-funcs cmake-utils unpacker
+inherit eutils toolchain-funcs cmake-utils
 
 MY_P="${PN}-dynamics-${P}"
 DESCRIPTION="an integrated solution for real time simulation of physics environments"
@@ -15,7 +15,7 @@ KEYWORDS="amd64 x86"
 IUSE=""
 
 RDEPEND=""
-DEPEND="$(unpacker_src_uri_depends)"
+DEPEND="app-arch/unzip"
 
 S=${WORKDIR}/${MY_P}