Add regex decorator to re string

Author: dshemetov

src/server/endpoints/covidcast_utils/model.py

@@ -47,7 +47,7 @@ def _fix_links(link: Optional[str]) -> List[WebLink]:
     if not link:
         return []
 
-    reg = re.compile("\[(.+)\]\s*\((.*)\)")
+    reg = re.compile(r"\[(.+)\]\s*\((.*)\)")
 
     def parse(l: str) -> Optional[WebLink]:
         l = l.strip()