Fix tests under Python 3.12

The error was in Tests.test_build_sdist_pep517_no_isolation:

    E           check_manifest.CommandFailed: ['/home/mg/src/check-manifest/.tox/py312/bin/python', '-m', 'build', '--sdist', '.', '--outdir', '/tmp/test-5rhghuor-check-manifest', '--no-isolation'] failed (status 1):
    E           * Getting build dependencies for sdist...
    E           running egg_info
    E           creating UNKNOWN.egg-info
    E           writing UNKNOWN.egg-info/PKG-INFO
    E           writing dependency_links to UNKNOWN.egg-info/dependency_links.txt
    E           writing top-level names to UNKNOWN.egg-info/top_level.txt
    E           writing manifest file 'UNKNOWN.egg-info/SOURCES.txt'
    E           reading manifest file 'UNKNOWN.egg-info/SOURCES.txt'
    E           writing manifest file 'UNKNOWN.egg-info/SOURCES.txt'
    E
    E           ERROR Missing dependencies:
    E               wheel

    check_manifest.py:168: CommandFailed

setup.py

@@ -66,6 +66,7 @@
         'test': [
             'mock >= 3.0.0; python_version == "3.7"',
             'pytest',
+            'wheel',
         ],
     },
     entry_points={