[fix] downgrade Mocha and Puppeteer for Node 8 support (#6803)

package.json

@@ -112,7 +112,7 @@
     "@rollup/plugin-typescript": "^2.0.1",
     "@rollup/plugin-virtual": "^2.0.0",
     "@sveltejs/eslint-config": "github:sveltejs/eslint-config#v5.7.0",
-    "@types/mocha": "^9.0.0",
+    "@types/mocha": "^7.0.0",
     "@types/node": "^8.10.53",
     "@typescript-eslint/eslint-plugin": "^4.31.2",
     "@typescript-eslint/parser": "^4.31.2",
@@ -131,9 +131,9 @@
     "kleur": "^3.0.3",
     "locate-character": "^2.0.5",
     "magic-string": "^0.25.3",
-    "mocha": "^9.0.0",
+    "mocha": "^7.0.0",
     "periscopic": "^3.0.4",
-    "puppeteer": "^10.0.0",
+    "puppeteer": "^2.0.0",
     "rollup": "^1.27.14",
     "source-map": "^0.7.3",
     "source-map-support": "^0.5.13",