test: fix config regression data spelling (#2240)

The lint job on PR #2241 failed in the codespell pre-commit hook because
the new write-preservation regression used "readded" as a sample value.
The same two diagnostics reproduce with codespell 2.4.3 locally.

Use "again" in both the assignment and assertion. The value is arbitrary:
the regression checks the spelling of a removed and recreated option,
so this satisfies lint without changing the behavior under test.

Validation: codespell passes for the three PR files; the affected test
passes on Python 3.14.7; Ruff lint and formatting pass for test_config.py.

Author: codex

test/test_config.py

@@ -159,8 +159,8 @@ def test_case_insensitive_writes_preserve_spelling(self, rw_dir):
             self.assertEqual(config.get_values("CORE", "BIGNAME"), [3, 4])
             self.assertTrue(config.remove_option("CORE", "NEWKEY"))
             self.assertFalse(config.has_option("core", "newkey"))
-            config.set_value("core", "newkey", "readded")
-            self.assertIn(("newkey", "readded"), config.items("CORE"))
+            config.set_value("core", "newkey", "again")
+            self.assertIn(("newkey", "again"), config.items("CORE"))
             self.assertTrue(config.remove_option("CORE", "NEWKEY"))
             config.rename_section('remote "Origin"', 'Remote "Other"')
             self.assertEqual(config.get('REMOTE "Other"', "URL"), "upper")