Fix a bug in actions artifact test (#32672)

This bug exists in `TestActionsArtifactDownload`.


https://github.com/go-gitea/gitea/blob/a1f56f83bff56f86180e59742efd3748908b82c1/tests/integration/api_actions_artifact_test.go#L123-L134

We assert that `listResp.Count` is `2`, so `artifactIdx` could be `0` or `1`.

https://github.com/go-gitea/gitea/blob/a1f56f83bff56f86180e59742efd3748908b82c1/tests/integration/api_actions_artifact_test.go#L144-L147

Then we assert that the length of `downloadResp.Value` is `1`. If
`artifactIdx` is `1` at this point, the assertion on Line 147 will throw
an `index out of range` error.

tests/integration/api_actions_artifact_test.go

@@ -144,12 +144,12 @@ func TestActionsArtifactDownload(t *testing.T) {
 	var downloadResp downloadArtifactResponse
 	DecodeJSON(t, resp, &downloadResp)
 	assert.Len(t, downloadResp.Value, 1)
-	assert.Equal(t, "artifact-download/abc.txt", downloadResp.Value[artifactIdx].Path)
-	assert.Equal(t, "file", downloadResp.Value[artifactIdx].ItemType)
-	assert.Contains(t, downloadResp.Value[artifactIdx].ContentLocation, "/api/actions_pipeline/_apis/pipelines/workflows/791/artifacts")
+	assert.Equal(t, "artifact-download/abc.txt", downloadResp.Value[0].Path)
+	assert.Equal(t, "file", downloadResp.Value[0].ItemType)
+	assert.Contains(t, downloadResp.Value[0].ContentLocation, "/api/actions_pipeline/_apis/pipelines/workflows/791/artifacts")
 
-	idx = strings.Index(downloadResp.Value[artifactIdx].ContentLocation, "/api/actions_pipeline/_apis/pipelines/")
-	url = downloadResp.Value[artifactIdx].ContentLocation[idx:]
+	idx = strings.Index(downloadResp.Value[0].ContentLocation, "/api/actions_pipeline/_apis/pipelines/")
+	url = downloadResp.Value[0].ContentLocation[idx:]
 	req = NewRequest(t, "GET", url).
 		AddTokenAuth("8061e833a55f6fc0157c98b883e91fcfeeb1a71a")
 	resp = MakeRequest(t, req, http.StatusOK)