fix: correct syntax error in handle_index by removing stray equals sign

src/rupload/app.py

@@ -268,7 +268,7 @@ async def handle_index(request: web.Request):
     if "is available here: " in message:
         url = message[message.find("here: ") + len("here: "):]
         message = message[: message.find("here: ")+len("here: ")]
-        message = += f"<a href=\"{url}\">"
+        message += f"<a href=\"{url}\">"
         message += f"{url}</a>"
     if message:
         message += "<br /><br />"