Update Purescript versions in tests

[keijokapp]

The 0.13.0 versions used in the tests does not work anymore due to dependency on libtinfo. That makes the installer to try to build the binary from source. It might work for real use cases (though it failed in my Ubuntu 20.04 container) but the tests fail because of the time limit.

I updated the versions in tests to the latest ones (0.15.x). I also removed one test because I'm not able to see what the test is supposed to test and what version should be used there.

[JordanMartinez]

Can we instead bump those to 0.14.0? AFAICT, the tests should be updated every time a new release is made.

The 0.15.0-alpha test probably existed because there wasn't a 0.15.0 release yet.

[keijokapp]

Hi! I might be missing something here. If the goal is to test that the latest major PS versions work, the new test versions should be 0.15.7 and 0.14.9.

If the goal is to just test the installer itself then

1. I don't see a reason not to use the latest PS versions - the goal would be to keep the versions working for as long as posible so they won't need to be changed that often;
2. I don't see an effective difference between the removed test and the 3rd test - they both try to install the version different from the previous test.