How to declare C:\Program Files\wkhtmltopdf\bin\wkhtmltopdf in .env using phpdotenv3

I want to know hot to set WKHTMLTOPDF='"C:\Program Files\wkhtmltopdf\bin\wkhtmltopdf"'

in .env for laravel using phpdotenv3 in order to make it work in project. I have same issue here https://github.com/vlucas/phpdotenv/issues/170 and here https://github.com/vlucas/phpdotenv/issues/133. This https://github.com/vlucas/phpdotenv/blob/master/UPGRADING.md did not help. How to fix it? Thanks

via Chebli Mohamed