Update ImplicitDifferentiation requirement to 0.9.1 in /docs (#204)

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
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/Project.toml

@@ -19,6 +19,7 @@ ADTypes = "1.21.0"
 ComponentArrays = "0.15.31"
 Documenter = "1.3"
 ForwardDiff = "1.3.1"
+ImplicitDifferentiation = "0.9.1"
 Literate = "2.21.0"
 NLsolve = "4.5.1"
 Zygote = "0.7.10"