Update test dependencies to support newer test runner

[Viir]

Running the latest version of elm-test-rs on this project failed with the following error message:

Error: Failed to solve dependencies for tests to run

Caused by:
    This version of elm-test-rs only supports elm-explorations/test 2.0.0 <= v < 3.0.0, but you have 1.1.0 <= v < 2.0.0 in your dependencies

The changes in this pull request update the dependencies to enable running tests with the latest version of elm-test-rs Changes in the API of the test framework required adaption of the test code. For details on changes in the test framework, see:

• https://github.com/elm-explorations/test/commit/e3584bddcbba7030f39dadcd6473469d72f6e372 (https://github.com/elm-explorations/test/pull/46, https://github.com/elm-explorations/test/issues/224)
• https://github.com/elm-explorations/test/commit/9aa32d9d28435d61d8c53d8b88023dd6c0bdab7e (https://github.com/elm-explorations/test/issues/48)
• https://github.com/elm-explorations/test/commit/387aa2d6ed53e6389f360529ca01c557a8116289 (https://github.com/elm-explorations/test/pull/157)