Require DiffEqFlux 4 (SciML#1273)

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>

Author: ChrisRackauckas-Claude

Project.toml

@@ -32,7 +32,7 @@ ArrayInterface = "7.10"
 Boltz = "1"
 ComponentArrays = ">= 0.13.9"
 ConsoleProgressMonitor = "0.1.1"
-DiffEqFlux = "2, 3, 4"
+DiffEqFlux = "4"
 DocStringExtensions = "0.9.5"
 FiniteDiff = "2"
 Flux = "0.13, 0.14, 0.15, 0.16"