Consider removing `mkl-service` requirements

[brandonwillard]

Looking at the codebase, it doesn't seem like we use the mkl-service package for anything other than two mkl.get_version_string() calls. If there's another way to get the version string, or skip the checks that use those calls altogether, then we should definitely get rid of this implicit mkl-service requirement.

Originally posted by @brandonwillard in https://github.com/conda-forge/aesara-feedstock/issues/80#issuecomment-1173196538