Normalize the encoding names for Latin-1 and UTF-8 to
'latin-1' and 'utf-8'.

These are optimized in the Python Unicode implementation
to result in more direct processing, bypassing the codec
registry.

Also see issue11303.
diff --git a/Lib/test/test_bigmem.py b/Lib/test/test_bigmem.py
index ac6b109..f9a0a3d 100644
--- a/Lib/test/test_bigmem.py
+++ b/Lib/test/test_bigmem.py
@@ -707,7 +707,7 @@
 class BytesTest(unittest.TestCase, BaseStrTest):
 
     def from_latin1(self, s):
-        return s.encode("latin1")
+        return s.encode("latin-1")
 
     @bigmemtest(minsize=_2G + 2, memuse=1 + character_size)
     def test_decode(self, size):
@@ -718,7 +718,7 @@
 class BytearrayTest(unittest.TestCase, BaseStrTest):
 
     def from_latin1(self, s):
-        return bytearray(s.encode("latin1"))
+        return bytearray(s.encode("latin-1"))
 
     @bigmemtest(minsize=_2G + 2, memuse=1 + character_size)
     def test_decode(self, size):