[ImgBot] Optimize images

*Total -- 17.43kb -> 7.03kb (59.64%)

/solution/0100-0199/0142.Linked List Cycle II/images/circularlinkedlist.png -- 11.04kb -> 4.03kb (63.45%)
/solution/0100-0199/0142.Linked List Cycle II/images/circularlinkedlist_test2.png -- 4.47kb -> 2.07kb (53.73%)
/solution/0100-0199/0142.Linked List Cycle II/images/circularlinkedlist_test3.png -- 1.92kb -> 0.93kb (51.45%)

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