build: bump Symbolics compat

Author: AayushSabharwal

Project.toml

@@ -158,7 +158,7 @@ StochasticDelayDiffEq = "1.10"
 StochasticDiffEq = "6.72.1"
 SymbolicIndexingInterface = "0.3.39"
 SymbolicUtils = "3.26.1"
-Symbolics = "6.37"
+Symbolics = "6.40"
 URIs = "1"
 UnPack = "0.1, 1.0"
 Unitful = "1.1"