chore(deps): bump github.com/stretchr/testify v1.12.1

[thaJeztah]

update testify to remove some deprecated indirect dependencies.

full diff: stretchr/testify@v1.11.1...v1.12.1

[thaJeztah]

cc @cyphar

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[thaJeztah]

Looks like golangci-lint may need to be updated; failing on go1.27

  Running [/home/runner/golangci-lint-2.12.2-linux-amd64/golangci-lint run] in [/home/runner/work/filepath-securejoin/filepath-securejoin] ...
  Error: ../../../../../opt/hostedtoolcache/go/1.27.1/x64/src/crypto/internal/randutil/randutil.go:11:2: could not import math/rand/v2 (/opt/hostedtoolcache/go/1.27.1/x64/src/math/rand/v2/rand.go:213:17: method must have no type parameters) (typecheck)
  	"math/rand/v2"
  	^
  Error: ../../../../../opt/hostedtoolcache/go/1.27.1/x64/src/crypto/internal/randutil/randutil.go:21:5: undefined: rand (typecheck)
  	if rand.Uint64()&1 == 1 {
  	   ^
  2 issues:
  * typecheck: 2
  * ```

[thaJeztah]

• opened ci: update golangci-lint to v2.13 for go1.27 compatibility, add go1.24, go1.25 #104 for the golangci-lint update