test: 修复测试例在app平台报错的问题

pages/component/canvas/canvas.test.js

 let page
 
-beforeAll(async () => {
+beforeAll(async () => {
+  if (!process.env.uniTestPlatformInfo.toLowerCase().startsWith('web')) {
+    return
+  }
   page = await program.reLaunch('/pages/component/canvas/canvas')
   await page.waitFor(2000)
 })