Merge pull request #1244 from SciML/compathelper/new_version/2021-08-31-00-10-45-848-03454761073

CompatHelper: bump compat for SymbolicUtils to 0.15, (keep existing compat)

Author: shashi

Project.toml

@@ -72,7 +72,7 @@ SciMLBase = "1.3"
 Setfield = "0.7"
 SpecialFunctions = "0.7, 0.8, 0.9, 0.10, 1.0"
 StaticArrays = "0.10, 0.11, 0.12, 1.0"
-SymbolicUtils = "0.13.4"
+SymbolicUtils = "0.13.4, 0.15"
 Symbolics = "3.1"
 UnPack = "0.1, 1.0"
 Unitful = "1.1"