change yaml format to match others

This solely changes the yaml format of `pgts_browser_list.yaml` allowing to change the testcases with tools like "ua-parser-tools".
No additional testcases are being added, nor testcases are changed.

The recipe to generate this file:

1. Checkout [ua-parser-tools](https://github.com/commenthol/ua-parser-tools)
2. Change in `config.js`
   config.ua_parser.test_resources.ua: 'test_resources/pgts_browser_list.yaml'
3. Run `node ua.js -u no -t`
4. Output is written in `report/test_resources/pgts_browser_list.yaml`
5. Voila