Singwai Chan

 I ran `test` on the master branch and saw this warning. The method is provided by third-party library, we should disable the warning for single line..

BUG: CSS Parser's shape doesn't allow the CSS property to be defined more than once.

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### GrapesJS version - [X] I confirm to use the latest version of GrapesJS ### What browser are you using? Any ### Reproducible demo link https://grapesjs.com/demo.html ### Describe the bug...