2.0.0

Raises the required package "jackiedo/dotenv-editor" from v1 to v2, to be compatible with current/ future PHP versions and the latest maintained "jackiedo/dotenv-editor" version.

As "jackiedo/dotenv-editor" v2 is a complete rewrite, there had to be done some rewriting in companienv as well. Also the tests cannot be run as "InMemory" like before. Nevertheless all Behat tests are still green.

Switched from travis to github/workflows to run the tests and static code analysis via GitHub actions.