Add default font support for argument font of TextClip

[Pandede]

Currently, the font argument requires users to provide the path to a TrueType font file. While this works well in most cases, it can be inconvenient for testing purposes, as it requires installing or specifying a font file beforehand.

To enhance usability, I propose leveraging the PIL.ImageFont API's load_default method, which allows loading a basic TrueType font without requiring prior installation. This would simplify the workflow, especially for testing or lightweight applications.