Fixed cache updated when not needed in CallbackTag

    @property

    def value(self):

        if self.ttl is not None or self.ttl is None and self._cache_last_update is None:

        # Update the cached value if it has expired or not retrieved yet:

        if self.ttl is not None or (self.ttl is None and self._cache_last_update is None):

            if self._cache_last_update is None or datetime.now() - self._cache_last_update > self.ttl:

                self.value = str(self.callback(**self._callback_extra))

        return self._cache_value