Given the head of a singly linked list, remove the $n^{th}$ node from the end of the list and return the head of the modified list.

Note: Could you solve this in a single pass through the list?

Constraints:

• The number of nodes in the list is sz

• $1 \leq$ sz $\leq 30$

• $0 \leq$ Node.val $\le 100$ ...