False positive on emptyRules with interpolation

[JoseLion]

When a rule has any content from interpolation, it should not report the emptyRules error/warning. This seems to be a regression on microsoft#50, which is weird because it seems there are tests to cover this 🤔

Versions:
@styled/typescript-styled-plugin: ^0.20.0
typescript: ^4.9.4

PS: The issue seems to be present in typescript-styled-plugin@0.18.2 too