markdown: Annotate code_escape(). (#7857)

Author: lucas-six

stubs/Markdown/markdown/util.pyi

@@ -18,7 +18,7 @@ RTL_BIDI_RANGES: Any
 def deprecated(message: str, stacklevel: int = ...): ...
 def isBlockLevel(tag: object) -> bool: ...
 def parseBoolValue(value, fail_on_errors: bool = ..., preserve_none: bool = ...): ...
-def code_escape(text): ...
+def code_escape(text: str) -> str: ...
 
 class AtomicString(str): ...