fix: mismatch between required Pillow version and monitoring implementation

[xamcost]

Hi there! To begin with, thank you for your amazing products. This tiny PR suggests a fix in example/monitoring.py, consisting of replacing ImageDraw.textsize and FreeTypeFont.getsize by textbbox and getbbox method respectively, since the former have been removed from Pillow versions greater than 9.5, whereas the currently requested version must be greater than 10.

Of course, we could alternatively change the Pillow version requirement. Up to you.