Don't use "b" for strings with '\uxxxx'.

This gives a SyntaxWarning in Python 3.12. In older Pythons it would
not warn, but in all cases it gives a literal raw \u (with a backslash)
instead of Unicode characters.

Python 2.x needed u'\uxxxx' but the u is no longer needed with 3.x.

test/framework/run.py

@@ -153,7 +153,7 @@ def test_run_cmd(self):
         # this is constructed to reproduce errors like:
         # UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe2
         # UnicodeEncodeError: 'ascii' codec can't encode character u'\u2018'
-        for text in [b"foo \xe2 bar", b"foo \u2018 bar"]:
+        for text in [b"foo \xe2 bar", "foo \u2018 bar"]:
             test_file = os.path.join(self.test_prefix, 'foo.txt')
             write_file(test_file, text)
             cmd = "cat %s" % test_file
@@ -182,7 +182,7 @@ def test_run_shell_cmd_basic(self):
         # UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe2
         # UnicodeEncodeError: 'ascii' codec can't encode character u'\u2018'
         # (such errors are ignored by the 'run' implementation)
-        for text in [b"foo \xe2 bar", b"foo \u2018 bar"]:
+        for text in [b"foo \xe2 bar", "foo \u2018 bar"]:
             test_file = os.path.join(self.test_prefix, 'foo.txt')
             write_file(test_file, text)
             cmd = "cat %s" % test_file