Replace IOError with OSError (#16715)
diff --git a/Lib/test/test_normalization.py b/Lib/test/test_normalization.py
index e3e2560..db28e1a 100644
--- a/Lib/test/test_normalization.py
+++ b/Lib/test/test_normalization.py
@@ -43,7 +43,7 @@
         try:
             testdata = open_urlresource(TESTDATAURL, encoding="utf-8",
                                         check=check_version)
-        except (IOError, HTTPException):
+        except (OSError, HTTPException):
             self.skipTest("Could not retrieve " + TESTDATAURL)
         self.addCleanup(testdata.close)
         for line in testdata: