In a separate terminal:
cd imgs/
The first time you run this:
cat *.png | ffmpeg -f image2pipe -i - ../out.avi && ffmpeg -i ../out.avi -pix_fmt rgb24 -loop 0 ../out.gif
In future iterations, this helps to remove the previous files:
rm ../out.avi ../out.gif && cat *.png | ffmpeg -f image2pipe -i - ../out.avi && ffmpeg -i ../out.avi -pix_fmt rgb24 -loop 0 ../out.gif