Update Plots requirement to 1.41.6 in /test

Updates the requirements on [Plots](https://github.com/JuliaPlots/Plots.jl) to permit the latest version.
- [Release notes](https://github.com/JuliaPlots/Plots.jl/releases)
- [Changelog](https://github.com/JuliaPlots/Plots.jl/blob/v2/NEWS.md)
- [Commits](JuliaPlots/Plots.jl@Plots-v1.41.5+docs...Plots-v1.41.6)

---
updated-dependencies:
- dependency-name: Plots
  dependency-version: 1.41.6
  dependency-type: direct:production
...

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Author: dependabot[bot]

test/Project.toml

@@ -24,4 +24,5 @@ DecisionFocusedLearningBenchmarks = {path = ".."}
 Aqua = "0.8.14"
 DecisionFocusedLearningBenchmarks = "0.6.0"
 JuliaFormatter = "2"
+Plots = "1.41.6"
 Test = "1"