Fix the error judgment and improve compatibility

[HarutakaMatsumoto]

In v1.0.5, TestMeasureNonnegativeDistance_2Dimension failed, so the error judgment has been fixed.
The discovery of this issue was delayed due to test changes in v1.0.5.
To prevent recurrence, we now use cmpopts.Equateapprox to define the error due to differences in models.

[Copilot]

Pull Request Overview

This PR fixes a failing test and improves floating-point comparison compatibility by addressing numerical precision issues in distance measurements. The changes ensure more robust testing by using approximate equality comparisons for floating-point values.

• Upgraded Go version from 1.18 to 1.21 and added go-cmp dependency for better floating-point comparison
• Fixed boundary condition check from strict inequality to less-than-or-equal-to in the GJK algorithm
• Updated all test assertions to use approximate equality with cmpopts.EquateApprox for consistent floating-point comparisons

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
go.mod	Updated Go version to 1.21 and added go-cmp v0.7.0 dependency
Measure_test.go	Replaced exact floating-point equality checks with approximate comparisons and updated expected test values
Measure.go	Fixed boundary condition check in GJK algorithm from strict to inclusive inequality

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[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

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