bpo-43144: Mark unicodedata's test_normalization as requiring network (GH-24650)

Co-authored-by: Arkadiusz Miƛkiewicz <arekm@maven.pl>
diff --git a/Lib/test/test_unicodedata.py b/Lib/test/test_unicodedata.py
index b552d2b..edfd860 100644
--- a/Lib/test/test_unicodedata.py
+++ b/Lib/test/test_unicodedata.py
@@ -320,6 +320,7 @@ def unistr(data):
         data = [int(x, 16) for x in data.split(" ")]
         return "".join([chr(x) for x in data])
 
+    @requires_resource('network')
     def test_normalization(self):
         TESTDATAFILE = "NormalizationTest.txt"
         TESTDATAURL = f"http://www.pythontest.net/unicode/{unicodedata.unidata_version}/{TESTDATAFILE}"