Manifest v3 update

[stephenkall]

Currently, Chrome Web Store states that "This extension may soon no longer be supported because it doesn't follow best practices for Chrome extensions".

Need to update the extension into the new Manifest V3 format before June/25

[Zasek]

Hi, I have tried to update this extension, but some bugs needs fixing, especially about the background color of some sites. #17
Maybe we can work on this issue together. I am not a JS programmer. I have tried my best :(