Use SparseArrays' in-place ldiv!() on 1.13+

[JamesWrigley]

The in-place ldiv!() has been backported now.

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API