chore(lint): modernize Go (#7536)

Use modern Go constructs through the modernize analyzer from the
golang.org/x/tools package.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

plugin/pkg/singleflight/singleflight.go

@@ -23,7 +23,7 @@ import "sync"
 // call is an in-flight or completed Do call
 type call struct {
 	wg  sync.WaitGroup
-	val interface{}
+	val any
 	err error
 }
 
@@ -38,7 +38,7 @@ type Group struct {
 // sure that only one execution is in-flight for a given key at a
 // time. If a duplicate comes in, the duplicate caller waits for the
 // original to complete and receives the same results.
-func (g *Group) Do(key uint64, fn func() (interface{}, error)) (interface{}, error) {
+func (g *Group) Do(key uint64, fn func() (any, error)) (any, error) {
 	g.mu.Lock()
 	if g.m == nil {
 		g.m = make(map[uint64]*call)

plugin/pkg/singleflight/singleflight_test.go

@@ -27,7 +27,7 @@ import (
 
 func TestDo(t *testing.T) {
 	var g Group
-	v, err := g.Do(1, func() (interface{}, error) {
+	v, err := g.Do(1, func() (any, error) {
 		return "bar", nil
 	})
 	if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
@@ -41,7 +41,7 @@ func TestDo(t *testing.T) {
 func TestDoErr(t *testing.T) {
 	var g Group
 	someErr := errors.New("some error")
-	v, err := g.Do(1, func() (interface{}, error) {
+	v, err := g.Do(1, func() (any, error) {
 		return nil, someErr
 	})
 	if err != someErr {
@@ -56,7 +56,7 @@ func TestDoDupSuppress(t *testing.T) {
 	var g Group
 	c := make(chan string)
 	var calls int32
-	fn := func() (interface{}, error) {
+	fn := func() (any, error) {
 		atomic.AddInt32(&calls, 1)
 		return <-c, nil
 	}