test: modify test package name

Try to ensure that only exported functions are tested.

Ref: https://github.com/tektoncd/community/blob/main/standards.md#go-packages

```
All exported functions should have tests
  * If your package is named "foo", prefer putting tests in a "foo_test" package in the same folder to ensure that only exported functions are tested
```

The shell command to search for test package names without the `_test` suffix is:
* `find . -name "*_test.go" | xargs grep -E '^package ' | grep -Ev '_test$' | grep -v '^./test' | sort`

pkg/apis/pipeline/v1/taskref_types_test.go

@@ -5,7 +5,7 @@ Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
-	http://www.apache.org/licenses/LICENSE-2.0
+    http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
@@ -14,47 +14,51 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package v1
+package v1_test
 
-import "testing"
+import (
+	"testing"
+
+	v1 "github.com/tektoncd/pipeline/pkg/apis/pipeline/v1"
+)
 
 func TestTaskRef_IsCustomTask(t *testing.T) {
 	tests := []struct {
 		name string
-		tr   *TaskRef
+		tr   *v1.TaskRef
 		want bool
 	}{{
 		name: "not a custom task - apiVersion and Kind are not set",
-		tr: &TaskRef{
+		tr: &v1.TaskRef{
 			Name: "foo",
 		},
 		want: false,
 	}, {
 		// related issue: https://github.com/tektoncd/pipeline/issues/6459
 		name: "not a custom task - apiVersion is not set",
-		tr: &TaskRef{
+		tr: &v1.TaskRef{
 			Name: "foo",
 			Kind: "Example",
 		},
 		want: false,
 	}, {
 		name: "not a custom task - kind is not set",
-		tr: &TaskRef{
+		tr: &v1.TaskRef{
 			Name:       "foo",
 			APIVersion: "example/v0",
 		},
 		want: false,
 	}, {
 		name: "custom task with name",
-		tr: &TaskRef{
+		tr: &v1.TaskRef{
 			Name:       "foo",
 			Kind:       "Example",
 			APIVersion: "example/v0",
 		},
 		want: true,
 	}, {
 		name: "custom task without name",
-		tr: &TaskRef{
+		tr: &v1.TaskRef{
 			Kind:       "Example",
 			APIVersion: "example/v0",
 		},

pkg/apis/pipeline/v1beta1/cluster_task_conversion_test.go

@@ -14,15 +14,17 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package v1beta1
+package v1beta1_test
 
 import (
 	"context"
 	"testing"
+
+	v1beta1 "github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
 )
 
 func TestClusterTaskConversionBadType(t *testing.T) {
-	good, bad := &ClusterTask{}, &Pipeline{}
+	good, bad := &v1beta1.ClusterTask{}, &v1beta1.Pipeline{}
 
 	if err := good.ConvertTo(context.Background(), bad); err == nil {
 		t.Errorf("ConvertTo() = %#v, wanted error", bad)