compat: drop DiffRules 0.1

Remove the stale pre-1.0 compatibility entry. Current Symbolics and NaNMath constraints already require DiffRules 1.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>

Author: ChrisRackauckas

lib/ModelingToolkitBase/Project.toml

@@ -114,7 +114,7 @@ DelayDiffEq = "5.61, 6"
 DiffEqBase = "7.4.2"
 DiffEqCallbacks = "4"
 DiffEqNoiseProcess = "5"
-DiffRules = "0.1, 1.0"
+DiffRules = "1"
 DifferentiationInterface = "0.6.47, 0.7"
 Distributed = "1"
 DocStringExtensions = "0.8, 0.9"