Fix DiffEqBase import in jacobiansparsity.jl test

Adds explicit DiffEqBase import to resolve UndefVarError that occurs
when running tests in SafeTestsets environment. The error manifested
in CI at line 70 where DiffEqBase.ODEFunction is called but DiffEqBase
was not directly imported, only available through transitive dependencies.

Fixes CI failure in PR SciML#3912 InterfaceI test group.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ChrisRackauckas

test/jacobiansparsity.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, SparseArrays, OrdinaryDiffEq
+using ModelingToolkit, SparseArrays, OrdinaryDiffEq, DiffEqBase
 
 N = 3
 xyd_brusselator = range(0, stop = 1, length = N)