ci: bump to go 1.23 (#453)

Upgrade to Go 1.23.

Upgrade also requires bumping `golangci-lint` to v1.62.2, and upgrading
third-party test versions for some failing cases.

internal/stack/stack.go

@@ -7,10 +7,10 @@ import (
 	"strings"
 )
 
-// Frames returns at most max callstack Frames, starting with its caller and
+// Frames returns at most mx callstack Frames, starting with its caller and
 // skipping skip Frames.
-func Frames(skip, max int) []runtime.Frame {
-	pc := make([]uintptr, max)
+func Frames(skip, mx int) []runtime.Frame {
+	pc := make([]uintptr, mx)
 	n := runtime.Callers(skip+2, pc)
 	if n == 0 {
 		return nil

internal/stack/stack_test.go

@@ -25,6 +25,7 @@ func TestMatchFirst(t *testing.T) {
 	first := stack.Match(0, func(_ runtime.Frame) bool { return true })
 	if first == nil {
 		t.Fatalf("nil match")
+		return
 	}
 	got := first.Function
 	expect := pkg + ".TestMatchFirst"