chore(deps): update LinearSolve requirement from 2, 3 to 2, 3, 4.2 (#220)

Updates the requirements on [LinearSolve](https://github.com/SciML/LinearSolve.jl) to permit the latest version.

Updates `LinearSolve` to 4.2.0
- [Release notes](https://github.com/SciML/LinearSolve.jl/releases)
- [Commits](https://github.com/SciML/LinearSolve.jl/commits)

---
updated-dependencies:
- dependency-name: LinearSolve
  dependency-version: 4.2.0
  dependency-type: direct:production
  dependency-group: all-julia-packages
...

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

Author: dependabot[bot]

docs/Project.toml

@@ -23,7 +23,7 @@ Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 DeepEquilibriumNetworks = "2"
 Documenter = "1"
 DocumenterCitations = "1"
-LinearSolve = "2, 3"
+LinearSolve = "2, 3, 4.2"
 Lux = "1"
 LuxCUDA = "0.3"
 MLDatasets = "0.7"