Enable automatic formatting for tests/ (#12761)

Author: AA-Turner

.ruff.toml

@@ -485,18 +485,4 @@ exclude = [
     "sphinx/transforms/*",
     "sphinx/util/*",
     "sphinx/writers/*",
-    "tests/*",
-    "tests/roots/*",
-    "tests/test_builders/*",
-    "tests/test_config/*",
-    "tests/test_directives/*",
-    "tests/test_domains/*",
-    "tests/test_environment/*",
-    "tests/test_extensions/*",
-    "tests/test_intl/*",
-    "tests/test_markup/*",
-    "tests/test_pycode/*",
-    "tests/test_transforms/*",
-    "tests/test_util/*",
-    "tests/test_writers/*",
 ]