provide required credentials for BrowserStack (#478)

GitHub Secrets are not available in GitHub Action triggered by pull request
created from fork. But we want to run BrowserStack based tests for them
as well. Adding the credentials as clear text again as it was the case
before #467.

.github/workflows/test-workflow.yml

@@ -115,8 +115,8 @@ jobs:
       - name: 'BrowserStack Env Setup'
         uses: 'browserstack/github-actions/setup-env@master'
         with:
-          username:  ${{ secrets.BROWSERSTACK_USERNAME }}
-          access-key: ${{ secrets.BROWSERSTACK_ACCESS_KEY }}
+          username: 'jeldrikhanschke1'
+          access-key: 'xaM9Uxurv2GyxFLKQXgj'
       - name: 'Start BrowserStackLocal Tunnel'
         uses: 'browserstack/github-actions/setup-local@master'
         with: