fix: reject invalid readiness user payload (#77)

src/main.py

@@ -43,6 +43,8 @@ async def readiness():
         user = await asyncio.wait_for(
             current_user(), timeout=READINESS_TIMEOUT_SECONDS
         )
+        if not isinstance(user, dict) or not user.get("login"):
+            raise ValueError("Gitea current-user response did not include a login")
     except Exception as exc:
         timed_out = isinstance(exc, TimeoutError)
         error_message = (