tests: Fix mocking of sleep calls with tenacity 8.4.2

Latest tenacity release adds some internal changes that broke the mocking of sleep calls in tests.

Fix it by directly mocking time.sleep (was not working previously).

swh/loader/git/tests/test_loader.py

@@ -1010,7 +1010,7 @@ class TestDumbGitLoaderWithPack(DumbGitLoaderTestBase):
 
     def test_http_get_retry(self, mocker, requests_mock):
         requests_mock.real_http = True
-        sleep = mocker.patch.object(dumb.GitObjectsFetcher._http_get.retry, "sleep")
+        sleep = mocker.patch("time.sleep")
 
         nb_files = 0
 
@@ -1040,7 +1040,7 @@ class TestDumbGitLoaderWithPack(DumbGitLoaderTestBase):
         assert res == {"status": "eventful"}
         sleep.assert_has_calls([mocker.call(param) for param in [1] * nb_files])
 
-        sleep = mocker.patch.object(dumb.check_protocol.retry, "sleep")
+        sleep = mocker.patch("time.sleep")
         with open(os.path.join(self.bare_repo_path, "info/refs"), "rb") as refs_data:
             requests_mock.get(
                 f"{self.repo_url}/info/refs",