fix: go runner with vendor folder

[not-matthias]

Fixes #24

[codspeed-hq]

CodSpeed Performance Report

Merging #25 will not alter performance

_{Comparing cod-1504-fix-go-runner-with-vendor-folder (90629b1) with main (e272453)}

Summary

✅ 24 untouched

[Copilot]

Pull Request Overview

This PR adds support for Go projects that use vendor directories by modifying the build command to use -mod=mod flag. This ensures that Go uses module mode instead of vendor mode, allowing the runner to work correctly with vendored dependencies.

• Added -mod=mod flag to the Go build command to force module mode
• Created a test case with a vendored project to verify the fix
• Added integration test coverage for the vendor folder scenario

Reviewed Changes

Copilot reviewed 6 out of 50 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
go-runner/src/builder/mod.rs	Added -mod=mod flag to force module mode during build
go-runner/src/integration_tests.rs	Added test case for example-with-vendor project
go-runner/testdata/projects/example-with-vendor/main.go	Created test project with basic functions for vendor testing
go-runner/testdata/projects/example-with-vendor/main_test.go	Created test and benchmark functions using vendored testify dependency
go-runner/testdata/projects/example-with-vendor/go.mod	Created module definition with testify dependency
go-runner/src/snapshots/codspeed_go_runner__integration_tests__assert_results_snapshots@example-with-vendor.snap	Added expected test results snapshot for vendor test case

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