Release prep: bump version to 0.4.0

Author: ChrisRackauckas

Project.toml

@@ -1,7 +1,7 @@
 name = "SymbolicAnalysis"
 uuid = "4297ee4d-0239-47d8-ba5d-195ecdf594fe"
 authors = ["Vaibhav Dixit <vaibhavyashdixit@gmail.com>", "Shashi Gowda <gowda@mit.edu>"]
-version = "0.3.8"
+version = "0.4.0"
 
 [deps]
 DSP = "717857b8-e6f2-59f4-9121-6e50c889abd2"