Remove stale OptimizationMOI MTK imports

Avoid importing ModelingToolkitBase bindings that are not declared at import time on newer Julia versions. The module already accesses ModelingToolkitBase through the MTK alias.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>

Author: ChrisRackauckas

lib/OptimizationMOI/src/OptimizationMOI.jl

@@ -7,7 +7,6 @@ using SciMLBase
 using SciMLStructures
 using SymbolicIndexingInterface
 using SparseArrays
-import ModelingToolkitBase: parameters, unknowns, varmap_to_vars, mergedefaults, toexpr
 import ModelingToolkitBase
 const MTK = ModelingToolkitBase
 using Symbolics