Type annotate StateBase.src property

Author: hukkinj1

markdown_it/ruler.py

@@ -41,11 +41,11 @@ def __init__(self, src: str, md: "MarkdownIt", env: MutableMapping):
         self.md = md
 
     @property
-    def src(self):
+    def src(self) -> str:
         return self._src
 
     @src.setter
-    def src(self, value):
+    def src(self, value: str) -> None:
         self._src = value
         self.srcCharCode = tuple(ord(c) for c in self.src)