devel/py-importlib-metadata: add explicit setuptools BUILD_DEPENDS

Per PEP-518 [0], for projects using setuptools as the build backend,
both setuptools and wheel are to be specified, as wheel is a plugin
for setuptools to support the format at all. Additionally, wheel
itself will soon [1] not depend on setuptools, but rather the
dependency tree will reverse.

With hat:	python
Approved by:	mentors (implicit), swills (maintainer, implicit)
References:	https://peps.python.org/pep-0518/#build-system-table [0]
		pypa/wheel#501 [1]

devel/py-importlib-metadata/Makefile

@@ -12,7 +12,8 @@ WWW=		https://github.com/python/importlib_metadata
 LICENSE=	APACHE20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
-BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}setuptools_scm>0:devel/py-setuptools_scm@${PY_FLAVOR} \
+BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}setuptools>=56:devel/py-setuptools@${PY_FLAVOR} \
+		${PYTHON_PKGNAMEPREFIX}setuptools_scm>0:devel/py-setuptools_scm@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}wheel>0:devel/py-wheel@${PY_FLAVOR}
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}zipp>=0.5:devel/py-zipp@${PY_FLAVOR}