deps: upgrade `webdriverio` to v7

package.json

@@ -138,7 +138,7 @@
     "url-polyfill": "^1.1.12",
     "verdaccio": "^4.8.0",
     "watchify": "3.11.1",
-    "webdriverio": "5.18.6",
+    "webdriverio": "^7.7.4",
     "webpack": "4.44.1",
     "whatwg-fetch": "3.6.2"
   },