Compatibility improvements

[jeeinn]

#142

The imagefilledpolygon function will not be compatible in php8.1

imagefilledpolygon(): Using the $num_points parameter is deprecated
#1 /www/app/vendor/amenadiel/jpgraph/src/image/Image.php(1611): imagefilledpolygon(Object(GdImage), Array, 4, 16777215)

[codeclimate[bot]]

Code Climate has analyzed commit 544e95fe and detected 10 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	1
Style	7
Clarity	2

View more on Code Climate.

[pierresh]

Hello,

It would be great that this pull request gets merged, thanks!