timeafter: skip check on Go ≥ 1.23

Go version ≥ 1.23 no longer has the issue of not collecting unstopped
Timers and time.After can safely be used in loops. Also see
https://go.dev/doc/go1.23#timer-changes and
https://cs.opensource.google/go/go/+/refs/tags/go1.23.2:src/time/sleep.go;l=196-201

Thus we can skip the timeafter check on modules with go.mod specifying
go1.23 or later.

Example run:

```
$ mkdir timeafter && cd timeafter
$ cat <<EOF > main.go
package main

import "time"

func main() {
	for {
		select {
		case <-time.After(5 * time.Second):
		}
	}
}
$ cat <<EOF > go.mod
module timeafter

go 1.22.0
EOF
$ linters .
/home/tklauser/tmp/timeafter/main.go:8:10: use of time.After in a for loop is prohibited, use inctimer instead
$ sed -ie 's/go 1\.22\.0/go 1.23.0/' go.mod
$ linters .
$
```

Signed-off-by: Tobias Klauser <[email protected]>

Author: tklauser

go.mod

@@ -4,10 +4,8 @@ go 1.22.0
 
 require (
 	golang.org/x/exp v0.0.0-20230809094429-853ea248256d
+	golang.org/x/mod v0.21.0
 	golang.org/x/tools v0.26.0
 )
 
-require (
-	golang.org/x/mod v0.21.0 // indirect
-	golang.org/x/sync v0.8.0 // indirect
-)
+require golang.org/x/sync v0.8.0 // indirect

timeafter/doc.go

@@ -2,7 +2,7 @@
 // Copyright Authors of Cilium
 
 // Package timeafter defines an Analyzer that checks for the use of time.After
-// in loops.
+// in loops on Go versions before 1.23
 //
 // # Analyzer timeafter
 //

timeafter/time_after.go

@@ -9,6 +9,7 @@ import (
 	"go/ast"
 	"strings"
 
+	"golang.org/x/mod/semver"
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/inspect"
 	"golang.org/x/tools/go/ast/inspector"
@@ -50,6 +51,21 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		return nil, errors.New("analyzer is not type *inspector.Inspector")
 	}
 
+	var goVersion string
+	if pass.Module != nil {
+		goVersion = pass.Module.GoVersion
+		if !strings.HasPrefix(goVersion, "v") {
+			goVersion = "v" + goVersion
+		}
+	}
+	if semver.Compare(goVersion, "v1.23.0") >= 0 {
+		// Go version ≥ 1.23 no longer has the issue of not collecting unstopped Timers and
+		// time.After can safely be used in loops. Also see
+		// https://go.dev/doc/go1.23#timer-changes and
+		// https://cs.opensource.google/go/go/+/refs/tags/go1.23.2:src/time/sleep.go;l=196-201
+		return nil, nil
+	}
+
 	ignoreMap := make(map[string]struct{})
 	for _, ign := range strings.Split(ignoreArg, ",") {
 		ignoreMap[strings.TrimSpace(ign)] = struct{}{}