upperbound Symbolics

this is to then start to release the next version with PR #1681

Author: shashi

Project.toml

@@ -1,7 +1,7 @@
 name = "ModelingToolkit"
 uuid = "961ee093-0014-501f-94e3-6117800e7a78"
 authors = ["Chris Rackauckas <[email protected]>"]
-version = "8.15.1"
+version = "8.15.2"
 
 [deps]
 AbstractTrees = "1520ce14-60c1-5f80-bbc7-55ef81b5835c"
@@ -71,7 +71,7 @@ Setfield = "0.7, 0.8, 1"
 SpecialFunctions = "0.7, 0.8, 0.9, 0.10, 1.0, 2"
 StaticArrays = "0.10, 0.11, 0.12, 1.0"
 SymbolicUtils = "0.19"
-Symbolics = "4.5"
+Symbolics = "4.5 - 4.8"
 UnPack = "0.1, 1.0"
 Unitful = "1.1"
 julia = "1.6"