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.

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