Update minimum go version to 1.22

Go 1.22 introduces language simplications which can be leveraged and
linters which can make use of it.

Signed-off-by: Derek McGowan <derek@mcg.dev>

Author: dmcgowan

go.mod

@@ -1,6 +1,6 @@
 module github.com/containerd/plugin
 
-go 1.20
+go 1.22
 
 require github.com/opencontainers/image-spec v1.1.0
 

plugin_test.go

@@ -520,15 +520,15 @@ func testPlugin(t Type, id string, i interface{}, err error) *Plugin {
 func BenchmarkGraph(b *testing.B) {
 	register := testRegistry()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		register.Graph(mockPluginFilter)
 	}
 }
 
 func BenchmarkUnique(b *testing.B) {
 	register := testRegistry()
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		checkUnique(register, &Registration{
 			Type: InternalPlugin,
 			ID:   "new",