Can't pull to refresh when swipe down on non-scrollable objects

**Describe the bug**
The swipe refresh only works for a scrollable object like ListView, SingleChildScrollView. And if "swipe down" performed on a non-scrollable object (Container, Text), the LiquidPullToRefresh not worked.

**To Reproduce**
Steps to reproduce the behavior:
1. Use this code: https://gist.github.com/IkhwanSI13/c38089a2ef6853b837e10a5988ec6475
2. Run the code
3. Swipe down at Container Text

**Expected behavior**
the onRefresh function of LiquidPullToRefresh runs when swiping down at Container Text.

**Flutter:**
- version: 1.22.6
- channel: stable

**Dart:**
- version: 2.10.5

**Additional context**
- liquid_pull_to_refresh: ^2.0.0

The issue is in the liquid_pull_to_refresh package. Start by examining the gesture detection logic in the main widget, likely in lib/liquid_pull_to_refresh.dart. The provided gist shows a minimal reproduction. Test by running the example and verifying that swipe down on a non-scrollable Container does not trigger onRefresh. Look for conditions that check scrollability. Done when the refresh works on any widget, not just scrollable ones.

Written by the indexing model from the issue text.