Update StochasticDiffEq requirement to 6.84.0

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

Updates `StochasticDiffEq` to 6.84.0
- [Release notes](https://github.com/SciML/StochasticDiffEq.jl/releases)
- [Commits](v0.0.1...v6.84.0)

---
updated-dependencies:
- dependency-name: StochasticDiffEq
  dependency-version: 6.84.0
  dependency-type: direct:production
  dependency-group: all-julia-packages
...

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Author: dependabot[bot]