Fix issue with `pngquant` and exit code 99 (#71)
Fix issue with `pngquant` and exit code 99 (#71)

Co-authored-by: Dave Thompson <664c8f5c4c7f9c1f2fd8c53adc3f00d224eb385d@3leaps.net>
Co-authored-by: Sindre Sorhus <734af6fcbad65feee4fc3cad1b3f8a05746ffb9a@gmail.com>
imagemin/imagemin-pngquant,imagemin/imagemin-pngquant