sysutils/duplicity: add ${PY_SETUPTOOLS} to BUILD_DEPENDS

setuptools-scm is not a PEP-517 build backend; add the real one.
Otherwise this build will fail once the linked PR is committed.

With hat: python
PR: 272134

sysutils/duplicity/Makefile

@@ -11,7 +11,8 @@ WWW=		https://duplicity.gitlab.io/
 LICENSE=	GPLv2+
 LICENSE_FILE=	${WRKSRC}/COPYING
 
-BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}setuptools_scm>0:devel/py-setuptools_scm@${PY_FLAVOR} \
+BUILD_DEPENDS=	${PY_SETUPTOOLS} \
+		${PYTHON_PKGNAMEPREFIX}setuptools_scm>0:devel/py-setuptools_scm@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}wheel>0:devel/py-wheel@${PY_FLAVOR}
 LIB_DEPENDS=	librsync.so:net/librsync
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}fasteners>=0:devel/py-fasteners@${PY_FLAVOR} \