Update changelog

Author: penelopeysm

HISTORY.md

@@ -9,6 +9,10 @@
 `DynamicPPL.TestUtils.AD.run_ad` now links the VarInfo by default.
 To disable this, pass the `linked=false` keyword argument.
 
+If the value or gradient calculated is not the same as the one calculated by the AD backend, instead of a test failing, the function now throws an `DynamicPPL.TestUtils.AD.ADIncorrectException`.
+The fields of this exception contain the expected and actual gradient, which you can inspect to see what went wrong.
+This also means that if you are using this function in a test suite, you need to use `@test run_ad(...) isa Any` rather than just `@test run_ad(...)`.
+
 ### VarInfo constructors
 
 `VarInfo(vi::VarInfo, values)` has been removed. You can replace this directly with `unflatten(vi, values)` instead.