DiffEqOperators.jl deprecated, update to SciMLOperators.jl

[neversakura]

See https://docs.sciml.ai/SciMLOperators/stable/sciml/ for details.

[neversakura]

Wait until issue is closed.

[vpuri3]

The transition is complete, barring a few niche features. You can safely switch to SciMLOperators. OrdinaryDiffEq, LinearSolve, etc, already use SciMLOperators.