Update ImplicitDifferentiation requirement to 0.9.1 in /test

Updates the requirements on [ImplicitDifferentiation](https://github.com/JuliaDecisionFocusedLearning/ImplicitDifferentiation.jl) to permit the latest version.
- [Release notes](https://github.com/JuliaDecisionFocusedLearning/ImplicitDifferentiation.jl/releases)
- [Commits](v0.1.0...v0.9.1)

---
updated-dependencies:
- dependency-name: ImplicitDifferentiation
  dependency-version: 0.9.1
  dependency-type: direct:production
...

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Author: dependabot[bot]

test/Project.toml

@@ -37,6 +37,7 @@ Documenter = "1.12.0"
 ExplicitImports = "1"
 FiniteDiff = "2.27.0"
 ForwardDiff = "0.10.36, 1"
+ImplicitDifferentiation = "0.9.1"
 JET = "0.9, 0.10, 0.11"
 KrylovKit = "0.10.2"
 LinearAlgebra = "1"