Pretty printer errors when a file is in the CWD

## Issue

The pretty printer errors when it tries to print a header for the test results of a file **if it is in the same working directory where the lest command was called.**

![image](https://github.com/TAServers/lest/assets/49565664/61f6a5ec-25c4-4e52-b8a0-289762599c40)

❌ This makes Lest unusable if the conditions specified above are met.