Enable the RUF043 lint in Ruff

.ruff.toml

@@ -262,6 +262,7 @@ select = [
 #    "RUF039",  # First argument to {call} is not raw string
     "RUF040",  # Non-string literal used as assert message
     "RUF041",  # Unnecessary nested `Literal`
+    "RUF043",  # Pattern passed to `match=` contains metacharacters but is neither escaped nor raw
 #    "RUF048",  # `__version__` may contain non-integral-like elements
     "RUF055",  # Plain string pattern passed to `re` function
 #    "RUF100",  # Unused `noqa` directive

tests/test_builders/test_build_html_maths.py

@@ -37,7 +37,7 @@ def test_html_math_renderer_is_duplicated(make_app, app_params):
     args, kwargs = app_params
     with pytest.raises(
         ConfigError,
-        match='Many math_renderers are registered. But no math_renderer is selected.',
+        match=r'Many math_renderers are registered\. But no math_renderer is selected\.',
     ):
         make_app(*args, **kwargs)
 
@@ -74,5 +74,8 @@ def test_html_math_renderer_is_chosen(app):
 )
 def test_html_math_renderer_is_mismatched(make_app, app_params):
     args, kwargs = app_params
-    with pytest.raises(ConfigError, match="Unknown math_renderer 'imgmath' is given."):
+    with pytest.raises(
+        ConfigError,
+        match=r"Unknown math_renderer 'imgmath' is given\.",
+    ):
         make_app(*args, **kwargs)