Fix float number in property value

[brd6]

Description

Updated NumberValueProperty class to handle decimal values by changing the type from int to float.

Motivation and context

Fixes an issue where decimal numbers in Notion databases were incorrectly rounded down, impacting data accuracy.

How has this been tested?

Tested in PHP 8.1, ensuring decimal numbers are now accurately handled without adverse side effects.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

PR checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• I have added tests to cover my changes.

[brd6]

Fix #31