Remove unused tests

The `test.sh` script is actually unused. It can be tested by using `npm test` instead.

```
$ git grep test-linked
.gitignore:tests/input/test-linked
scripts/test.sh:if [ -L ./test-linked ]; then
scripts/test.sh:    rm ./test-linked;
scripts/test.sh:ln -sf ./test2 ./test-linked
```