[stdlib] Mark constants as Final (#14577)

stdlib/html/entities.pyi

@@ -1,6 +1,8 @@
+from typing import Final
+
 __all__ = ["html5", "name2codepoint", "codepoint2name", "entitydefs"]
 
-name2codepoint: dict[str, int]
-html5: dict[str, str]
-codepoint2name: dict[int, str]
-entitydefs: dict[str, str]
+name2codepoint: Final[dict[str, int]]
+html5: Final[dict[str, str]]
+codepoint2name: Final[dict[int, str]]
+entitydefs: Final[dict[str, str]]