docs: add PreallocationTools.jl to docs environment

Author: AayushSabharwal

docs/Project.toml

@@ -15,6 +15,7 @@ Optimization = "7f7a1694-90dd-40f0-9382-eb1efda571ba"
 OptimizationOptimJL = "36348300-93cb-4f02-beb5-3c3902f8871e"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"
+PreallocationTools = "d236fae5-4411-538c-8e31-a6e3d9e00b46"
 SciMLStructures = "53ae85a6-f571-4167-b2af-e1d143709226"
 Setfield = "efcf1570-3423-57d1-acb7-fd33fddbac46"
 StochasticDiffEq = "789caeaf-c7a9-5a7d-9973-96adeb23e2a0"