Use pypa/build in favor of pep517.build

`pep517.build` is deprecated and has various bugs related to isolation,
and `pypa/build` has matured quite a bit.

Author: pganssle

tox.ini

@@ -73,12 +73,12 @@ commands =
 description = Build a wheel and source distribution
 skip_install = True
 deps =
-    pep517
+    build
     twine
 commands =
     python -c "from pathlib import Path; \
                [x.unlink(missing_ok=True) for x in Path('{toxinidir}/dist').glob('*')]"
-    python -m pep517.build -s -b {toxinidir} -o {toxinidir}/dist
+    python -m build -s -w -o {toxinidir}/dist {toxinidir}
     twine check {toxinidir}/dist/*
 
 [testenv:release]