Fix app.yaml.
Fix app.yaml.

GoogleCloudPlatform/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer,dq922/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer,dq922/PerfKitExplorer,dq922/PerfKitExplorer,GoogleCloudPlatform/PerfKitExplorer,dq922/PerfKitExplorer