Re-activate CompatHelper

[ranocha]

https://github.com/symengine/SymEngine.jl/actions/workflows/CompatHelper.yml:

This scheduled workflow is disabled because there hasn't been activity in this repository for at least 60 days. Enable this workflow to resume scheduled runs.

There has been an update of SymbolicUtils.jl. It would be nice to update the compat bounds accordingly. See the release notes at https://github.com/JuliaSymbolics/SymbolicUtils.jl/releases/tag/v4.0.0