vendor: update buildkit to v0.32.0-rc1

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

policy/validate_test.go

@@ -904,7 +904,7 @@ decision := {
 `),
 		}},
 		Env: Env{
-			Args:     map[string]*string{"MODE": stringPtr("prod")},
+			Args:     map[string]*string{"MODE": new("prod")},
 			Filename: "Dockerfile",
 			Target:   "release",
 		},
@@ -988,10 +988,6 @@ decision := {
 	require.ErrorContains(t, err, `unknown policy cap "exec.unknown"`)
 }
 
-func stringPtr(v string) *string {
-	return &v
-}
-
 func mustMarshalImageConfig(t *testing.T, img ocispecs.Image) []byte {
 	t.Helper()
 	dt, err := json.Marshal(img)