Bump webdriver-manager from 12.1.7 to 12.1.8

Bumps [webdriver-manager](https://github.com/angular/webdriver-manager) from 12.1.7 to 12.1.8.
- [Release notes](https://github.com/angular/webdriver-manager/releases)
- [Changelog](https://github.com/angular/webdriver-manager/blob/legacy/CHANGELOG.md)
- [Commits](angular/webdriver-manager@12.1.7...12.1.8)

---
updated-dependencies:
- dependency-name: webdriver-manager
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

package.json

@@ -117,6 +117,6 @@
     "tslint-config-prettier": "^1.18.0",
     "typescript": "3.8.3",
     "wait-on": "3.3.0",
-    "webdriver-manager": "12.1.7"
+    "webdriver-manager": "12.1.8"
   }
 }