Day18: Add another solution

Decided to (re)learn scala-graph. That was worth it.

Author: rolandtritsch

docs/2024/puzzles/day18.md

@@ -179,6 +179,7 @@ def part2(str: String): Vec2i =
 - [Solution](https://github.com/jnclt/adventofcode2024/blob/main/day18/ram-run.sc) by [jnclt](https://github.com/jnclt)
 - [Solution](https://github.com/aamiguet/advent-2024/blob/main/src/main/scala/ch/aamiguet/advent2024/Day18.scala) by [Antoine Amiguet](https://github.com/aamiguet)
 - [Solution](https://github.com/AvaPL/Advent-of-Code-2024/tree/main/src/main/scala/day18) by [Paweł Cembaluk](https://github.com/AvaPL)
+- [Solution](https://github.com/rolandtritsch/scala3-aoc-2024/blob/trunk/main/src/aoc2024/Day18.scala) by [Roland Tritsch](https://github.com/rolandtritsch)
 
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