fix: consistent std::int32_t in AdaptiveGridTrackDensity (#3933)

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## Summary by CodeRabbit

- **Bug Fixes**
	- Improved type consistency for the `getBin` method in the Adaptive Grid Track Density class, ensuring reliable bin calculations. 

This change enhances the overall stability of the feature without altering its functionality.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Core/src/Vertexing/AdaptiveGridTrackDensity.cpp

@@ -43,7 +43,7 @@ double AdaptiveGridTrackDensity::getBinCenter(std::int32_t bin,
 }
 
 std::int32_t AdaptiveGridTrackDensity::getBin(double value, double binExtent) {
-  return static_cast<int>(std::floor(value / binExtent - 0.5) + 1);
+  return static_cast<std::int32_t>(std::floor(value / binExtent - 0.5) + 1);
 }
 
 std::uint32_t AdaptiveGridTrackDensity::getTrkGridSize(