[FEATURE] is it possible to keep bootstrap.css file and use another signle css file?

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Describe the solution you'd like
I just saw the bootstrap.css is in adminlte.css, I am thinking is it possible to keep bootstrap.css no change and use another signle file for all achanges?

Describe alternatives you've considered
keep bootstrap.css and use single css file for all adminlte changes will better for manage and future support.

btw v4 is good.