Fixes #148 - prevents recursive calls to observer
Fixes #148 - prevents recursive calls to observer

Uses a block list for the attributes that shouldn't trigger the observer. It may be better to use an allow list since the observer is still called unnecessarily for e.g. `style` attribute changes.

shoelace-style/shoelace,claviska/shoelace-css,shoelace-style/shoelace,claviska/shoelace-css,shoelace-style/shoelace