Remove github.com/stretchr/testify and rely only in GO testing package

[gab-arrobo]

Also create a patch release

[Copilot]

Pull Request Overview

This PR removes the github.com/stretchr/testify dependency and migrates all tests to use Go's standard testing package. The change also updates test data URLs from NCTU references to Aether project URLs and creates a patch release by updating the version from 1.5.6-dev to 1.5.6.

Key changes:

• Replaced assert and require assertions with standard Go if checks and t.Error/t.Errorf/t.Fatalf calls
• Updated test fixture URLs from NCTU/free5gc to Aether project URLs
• Removed testify from dependencies and cleaned up indirect dependencies

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
httpwrapper/httpwrapper_test.go	Converted testify assertions to standard Go testing, updated test URLs to Aether project
go.mod	Removed stretchr/testify and related indirect dependencies
fsm/fsm_test.go	Replaced assert/require calls with standard Go error checking
flowdesc/ip_filter_rule_test.go	Migrated from testify assertions to Go testing with Fatalf for errors
flowdesc/ip_filter_rule_field_test.go	Converted require assertions to standard error handling
VERSION	Updated version from 1.5.6-dev to 1.5.6 for patch release

Comments suppressed due to low confidence (1)

go.mod:3

• Go 1.24.0 does not exist. As of January 2025, the latest Go version is 1.23.x. Please verify and use a valid Go version.

go 1.24.0

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