Fix typos in RUF043.py (astral-sh#15044)

(Accidentally introduced in astral-sh#14966.)

crates/ruff_linter/resources/test/fixtures/ruff/RUF043.py

@@ -78,8 +78,8 @@ def test_foo():
     with pytest.raises(Tab, match="\\t"): ...
     with pytest.raises(VerticalTab, match="\\v"): ...
     with pytest.raises(HexEscape, match="\\xFF"): ...
-    with pytest.raises(_16BitUnicodeEscape, match="\\FFFF"): ...
-    with pytest.raises(_32BitUnicodeEscape, match="\\0010FFFF"): ...
+    with pytest.raises(_16BitUnicodeEscape, match="\\uFFFF"): ...
+    with pytest.raises(_32BitUnicodeEscape, match="\\U0010FFFF"): ...
 
     ## Escaped metasequences