tests: xfail test_pip_install_no_binary on Python 3.7

The test case fails due to the new release of setuptools_scm, which now depends on importlib-metadata for 'python_version < "3.8"'. Due to the fact that importlib-metadata itself depends on setuptools_scm, it's not possible anymore to "pip install --no-binary importlib-metadata" on Python 3.7.

tests/integration/test_pep517.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import platform
+
 from pathlib import Path
 from typing import TYPE_CHECKING
 
@@ -75,6 +77,11 @@ def test_pip_wheel_build(temporary_directory: Path, project_source_root: Path) -
     assert len(wheels) == 1
 
 
+@pytest.mark.xfail(
+    tuple(int(part) for part in platform.python_version_tuple()[:2]) < (3, 8),
+    # see https://github.com/python/importlib_metadata/issues/392
+    reason="importlib-metadata can't be installed with --no-binary anymore",
+)
 def test_pip_install_no_binary(python: str, project_source_root: Path) -> None:
     subprocess_run(
         python,