@supports not correctly minified

[Ruud-Zuiderlicht]

@supports can't be used at the moment. The CSS code below should come out unaltered (already minified). However the closing bracket is removed.

steps to reproduce

echo \CssMin::minify('@supports(display:grid){.example{display:grid}}');

expected output string(47): "@supports(display:grid){.example{display:grid}}"

actual output string(46): "@supports(display:grid){.example{display:grid}"