Remove need to adjust `.vscode/launch.json` across days

[Cormochamelion]

When working in vscode, it's a very minor annoyance to change the day in .vscode/launch.json when debugging a new day. Luckily vscode does offer variables for lauch.json. To simplify this. Using ${fileBasenameNoExtension} here should do the trick.

Maybe there is a case here that people might want to have the debugger always run on the same file regardless of what's open, but they already had to edit launch.json if that file wasn't for day anyways. This way, everyone who want's to just have the debugger run on the current file get's a quality of life upgrade while nothing much changes for the others.