Update FiniteDiff requirement to 2.29.0 in /docs (#207)

Updates the requirements on [FiniteDiff](https://github.com/JuliaDiff/FiniteDiff.jl) to permit the latest version.
- [Release notes](https://github.com/JuliaDiff/FiniteDiff.jl/releases)
- [Commits](https://github.com/JuliaDiff/FiniteDiff.jl/commits)

---
updated-dependencies:
- dependency-name: FiniteDiff
  dependency-version: 2.29.0
  dependency-type: direct:production
...

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Author: dependabot[bot]

docs/Project.toml

@@ -19,6 +19,7 @@ ADTypes = "1.21.0"
 ComponentArrays = "0.15.31"
 DifferentiationInterface = "0.7.14"
 Documenter = "1.3"
+FiniteDiff = "2.29.0"
 ForwardDiff = "1.3.1"
 ImplicitDifferentiation = "0.9.1"
 Literate = "2.21.0"