Hotfix for breaking change in Optim.jl

[MilesCranmer]

Emergency fix due to breaking change in Optim.jl:

JuliaNLSolvers/Optim.jl#1046

[github-actions]

Benchmark Results

	master	8a38aeb...	t[master]/t[8a38aeb...]
search/multithreading	59.2 ± 4.1 s	0.0168 ± 0.0016 h	0.978
search/serial	56.1 ± 1 s	59.8 ± 3.7 s	0.938
time_to_load	2.5 ± 0.004 s	2.49 ± 0.012 s	1
utils/best_of_sample	1.6 ± 0.6 μs	1.6 ± 0.5 μs	1
utils/check_constraints_x10	18.5 ± 4.8 μs	18.5 ± 4.8 μs	1
utils/compute_complexity_x10/Float64	3.3 ± 0.1 μs	3.2 ± 0.1 μs	1.03
utils/compute_complexity_x10/Int64	3.3 ± 0.1 μs	3.3 ± 0.2 μs	1
utils/compute_complexity_x10/nothing	2.2 ± 0.1 μs	2.3 ± 0.2 μs	0.957
utils/optimize_constants_x10	0.0483 ± 0.011 s	0.0495 ± 0.011 s	0.975

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).