[ImgBot] Optimize images

*Total -- 9,588.64kb -> 4,469.09kb (53.39%)

/solutions/8.guest/2021/3.tessellation/terrain_cpu_src/resources/heightmaps/river2_heightmap.png -- 1,293.45kb -> 576.86kb (55.4%)
/solutions/8.guest/2021/3.tessellation/terrain_gpu_dist/resources/heightmaps/river2_heightmap.png -- 1,293.45kb -> 576.86kb (55.4%)
/solutions/8.guest/2021/3.tessellation/terrain_gpu_dist/resources/heightmaps/iceland_heightmap.png -- 1,457.42kb -> 670.04kb (54.03%)
/solutions/8.guest/2021/3.tessellation/terrain_cpu_src/resources/heightmaps/iceland_heightmap.png -- 1,457.42kb -> 670.04kb (54.03%)
/solutions/8.guest/2021/3.tessellation/terrain_cpu_src/resources/heightmaps/river_heightmap.png -- 2,043.45kb -> 987.64kb (51.67%)
/solutions/8.guest/2021/3.tessellation/terrain_gpu_dist/resources/heightmaps/river_heightmap.png -- 2,043.45kb -> 987.64kb (51.67%)

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