build(deps): update ModelingToolkitStandardLibrary requirement to 2.28.0

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

Updates `ModelingToolkitStandardLibrary` to 2.28.0
- [Release notes](https://github.com/SciML/ModelingToolkitStandardLibrary.jl/releases)
- [Commits](v0.1.0...v2.28.0)

---
updated-dependencies:
- dependency-name: ModelingToolkitStandardLibrary
  dependency-version: 2.28.0
  dependency-type: direct:production
  dependency-group: all-julia-packages
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/Project.toml

@@ -17,6 +17,7 @@ DataInterpolations = "6.4, 7, 8"
 Documenter = "1"
 IfElse = "0.1"
 ModelingToolkit = "11"
+ModelingToolkitStandardLibrary = "2.28.0"
 OrdinaryDiffEq = "6, 7"
 Plots = "1.36"
 SciCompDSL = "1"