fix: use value instead of score in BeatmapLeaderboardScore.Tooltip setter

The fork uses C# 13 `field` keyword so there's no explicit `score` backing
field in scope. The upstream-merged line incorrectly referenced `score`;
`value` (the setter parameter) is the correct variable here.

Author: Copilot

osu.Game/Screens/Select/BeatmapLeaderboardScore.Tooltip.cs

@@ -119,7 +119,7 @@ public ScoreInfo Score
                             new StatisticRow(s.DisplayName.ToUpper(), s.Count.ToLocalisableString("N0"), colours.ForHitResult(s.Result)));
 
                         var ruleset = value.Ruleset.CreateInstance();
-                        var scoreMultiplierCalculator = ruleset.CreateScoreMultiplierCalculator(new ScoreMultiplierContext(score.BeatmapInfo!.Difficulty));
+                        var scoreMultiplierCalculator = ruleset.CreateScoreMultiplierCalculator(new ScoreMultiplierContext(value.BeatmapInfo!.Difficulty));
                         double multiplier = scoreMultiplierCalculator.CalculateFor(value.Mods);
 
                         var generalStatistics = new[]