Conversion format from polygon ground truth to [xmin, ymin, xmax, ymax] format

I'm working with Mask RCNN network and variable boxes need to be in format [xmin, ymin, xmax, ymax] but can't transform one format in another.

Is there some way how can I convert this format:

             [
                [
                    21.51514273595292,
                    96.10111281287746
                ],
                [
                    34.41549485283264,
                    97.283756254127
                ],
                [
                    36.42017833821299,
                    98.51023290725634
                ],
                [
                    48.266909960703956,
                    99.59706074137782
                ],
                [
                    51.456108522323206,
                    92.58403315228024
                ],
                [
                    63.3249196091766,
                    93.6674491203431
                ],
                [
                    60.960257769931985,
                    110.16062344395255
                ],
                [
                    49.094275907517556,
                    109.06503983039966
                ],
                [
                    46.79115225196064,
                    109.89584392001012
                ],
                [
                    34.94618448639528,
                    108.80142524223687
                ],
                [
                    32.794444829218214,
                    108.60261473324032
                ],
                [
                    19.896204045991865,
                    107.41087863881067
                ],
                [
                    21.51514273595292,
                    96.10111281287746
                ]
            ] 

into this format: [xmin, ymin, xmax, yman]

The upper (bigger one) format is polygon ground truth (x,y, coordinates) of text on image.