⬆️ Bump webdriverio from 7.26.0 to 8.21.0

Bumps [webdriverio](https://github.com/webdriverio/webdriverio/tree/HEAD/packages/webdriverio) from 7.26.0 to 8.21.0.
- [Release notes](https://github.com/webdriverio/webdriverio/releases)
- [Changelog](https://github.com/webdriverio/webdriverio/blob/main/CHANGELOG.md)
- [Commits](https://github.com/webdriverio/webdriverio/commits/v8.21.0/packages/webdriverio)

---
updated-dependencies:
- dependency-name: webdriverio
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -51,7 +51,7 @@
     "nyc": "^15.1.0",
     "tsd": "^0.24.1",
     "wd": "^1.14.0",
-    "webdriverio": "^7.25.4"
+    "webdriverio": "^8.21.0"
   },
   "bugs": {
     "url": "https://github.com/percy/percy-appium-js/issues"