use-errors-new: disable for Go 1.26

[alexandear]

For unformatted strings, fmt.Errorf("x") in Go 1.26 allocates less and generally matches the allocations for errors.New("x"). See https://go.dev/doc/go1.26#fmtpkgfmt

[Copilot]

Pull request overview

This PR updates the use-errors-new lint rule to be effectively disabled for Go 1.26+ codebases, aligning the rule’s guidance with the Go 1.26 fmt.Errorf optimization for non-formatting usage.

Changes:

• Skip use-errors-new analysis when the package Go version is at least 1.26.
• Add Go 1.26 test fixtures (nested testdata/go1.26 module) to validate the rule is disabled.
• Introduce a lint.Go126 version constant and extend the unit test to cover the new fixture.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
rule/use_errors_new.go	Adds Go 1.26+ early return to disable rule execution.
lint/package.go	Adds Go126 version constant used by rules for version gating.
test/use_errors_new_test.go	Runs the rule against the Go 1.26-scoped fixture.
testdata/go1.26/go.mod	Declares a Go 1.26 nested module for version detection in tests.
testdata/go1.26/use_errors_new.go	Fixture ensuring fmt.Errorf("literal") is not flagged under Go 1.26.

[denisvmedia]

LGTM

[ccoVeille]

What about something in the rules description file